The major archaeological center of the United States, the Four Corners area -- where the states of Colorado, New Mexico, Arizona, and Utah meet -- is surrounded by a vast complex of ancient villages that dominated this region a thousand years ago. Here among the reddish-brown rocks, abandoned canyons, and flat mesas, you'll discover another world, once ruled by the ancestral Puebloans and today largely the domain of the Navajo.

In addition to the archaeological sites discussed below, the Crow Canyon Archaeological Center, 23390 Rd. K, Cortez, CO 81321-9408 (tel. 800/422-8975 or 970/565-8975; www.crowcanyon.org), offers tours of its current excavation sites. The full-day tours are offered Wednesday and Thursday from May through September, and cost $55 for adults and $30 for youths from 10 to 17 (children under 10 are not permitted). Lunch is included. Call ahead for reservations.

For those who want to dig in the dirt or help in the lab, Crow Canyon Archaeological Center offers week-long archeology research and lab programs, open to adults only, for about $1,400. Participants work side by side with professional archeologists, either in the field or the lab. There is also a Family Archeology Week in July, with hands-on activities. Cost is about $1,400 for adults and $1,125 for youths 10 to 17 (children under 10 are not permitted). See the center's website for details.

Hovenweep National Monument, CO/UT

Preserving some of the most striking and isolated archaeological sites in the Four Corners area, this national monument straddles the Colorado-Utah border, 40 miles west of Cortez.

Hovenweep is the Ute word for "deserted valley," appropriate because its inhabitants apparently left around 1300. The monument contains six separate sites and is noted for mysterious, 20-foot-high sandstone towers, some square, others oval, circular, or D-shaped. Archaeologists have suggested their possible function as everything from guard or signal towers, celestial observatories, and ceremonial structures to water towers or granaries.

A ranger station, with exhibits, restrooms, and drinking water, is at the Square Tower Group, in the Utah section of the monument, the most impressive and best preserved of the sites. The Hovenweep Campground, with 30 sites, is open year-round. Sites are fairly small -- most appropriate for tents or small pickup-truck campers -- but a few sites can accommodate RVs up to 36 feet long. The campground has flush toilets, drinking water, picnic tables, and fire pits, but no showers or RV hookups. Cost is $10 per night; reservations are not accepted, but the campground rarely fills.

From Cortez, take U.S. 160 south to County Road G (McElmo Canyon Rd.), and follow signs into Utah and the monument. The other five sites are difficult to find, and you'll need to obtain detailed directions and check on current road conditions before setting out. Summer temperatures can reach over 100°F (38°C), and water supplies are limited, so take your own and carry a canteen, even on short walks. Bug repellent is advised; gnats can be a nuisance in late spring.

The visitor center/ranger station is open daily from 8am to 6pm from May through September and 8am to 5pm the rest of the year; it's closed New Year's Day, Thanksgiving, and Christmas. Admission for up to a week costs $6 per vehicle or $3 per person on bike, motorcycle, or foot. For advance information, contact Hovenweep National Monument, McElmo Route, Cortez, CO 81321 (tel. 970/562-4282, ext. 10; www.nps.gov/hove). Allow a half-day for the Square Tower Group and at least 1 full day to visit Square Tower plus a few other sites.

Ute Mountain Tribal Park, CO

If you liked Mesa Verde but would have enjoyed it more without the company of so many fellow tourists, you'll love the Ute Mountain Tribal Park, P.O. Box 109, Towaoc, CO 81334 (tel. 800/847-5485 or 970/565-3751 ext. 330; www.utemountainute.com/tribalpark.htm).

Set aside by the Ute Mountain tribe to preserve its heritage, the 125,000-acre park -- which abuts Mesa Verde National Park -- includes wall paintings and ancient petroglyphs, as well as hundreds of surface sites and cliff dwellings that are similar in size and complexity to those in Mesa Verde.

Access to the park is limited to guided tours. Full- and half-day tours begin at the Ute Mountain Visitor Center & Museum (tel. 970/749-1452) at the junction of U.S. 491 and U.S. 160, 20 miles south of Cortez. Mountain-biking and backpacking trips are also offered. No food, water, lodging, gasoline, or other services are available within the park. Some climbing of ladders and a 3-mile walk are necessary on the full-day tour; the half-day tour involves only short walks from the road. The tours are on gravel roads.

Charges for tours in your vehicle start at $28 per person for a half-day, $48 for a full day; it's $10 per person extra to go in the tour guide's vehicle, and reservations are required. Special tours to remote sections of the park are also offered, with a minimum of four persons, at $60 per person per day. These include 5.6 miles of hiking and some climbing. Cost for private tours is $100 per person. Credit cards are not accepted (cash or checks only), dogs are not permitted on the property, and professional photography is not allowed.

There's a primitive campground ($12 per vehicle; reservations required), and primitive cabins ($10 per person; reservations required).

Cortez Cultural Center, CO

Housed in a historic 1909 building, the cultural center, 25 N. Market St., Cortez (tel. 970/565-1151; www.cortezculturalcenter.org), includes a museum with exhibits on both prehistoric and modern American Indians, an art gallery with displays of regional art, and a good gift shop offering crafts by local tribal members. A variety of programs are offered year-round, ranging from guided kids' hikes to photo exhibits, and from late May through early September there are American Indian dances and cultural programs Monday through Saturday evenings starting at 7:30pm, and following the dances, at 8:30pm, talks are given by historians, artists, and sometimes storytellers. The center is open daily from 10am to 10pm from June through August, with shorter hours the rest of the year. Admission is free, and you should plan to spend at least an hour in the museum (more if there are dances or other programs).

Nearby, the Hawkins Preserve covers 122 acres, offers hiking trails and rock-climbing opportunities, and includes several prehistoric archaeological sites. Check with the Cortez Cultural Center about current tours and other activities.

Anasazi Heritage Center, CO

When the Dolores River was dammed and McPhee Reservoir created in 1985, some 1,600 ancient archaeological sites were threatened. Four percent of the project cost was set aside for archaeological work, and several million artifacts and other prehistoric items were rescued. Many are on display here. Located 10 miles north of Cortez, the center is set in a hillside near the remains of 12th-century sites.

Operated by the Bureau of Land Management, the center emphasizes visitor involvement. Children and adults are invited to examine corn-grinding implements, a loom and other weaving materials, and a re-created pit house. You can touch artifacts 1,000 to 2,000 years old, examine samples through microscopes, use computer programs, and engage in video lessons in archaeological techniques.

A half-mile-long, wheelchair-accessible trail leads from the museum to the small Dominguez Pueblo Ruins, atop a low hill, with a beautiful view across the Montezuma Valley. It was probably home to a family of four to six people and has low walls marking four rooms. Nearby are ruins of the much larger Escalante Pueblo, with about 28 rooms surrounding a kiva. Archaeologists say that Escalante Pueblo was one of the northernmost settlements influenced by the Chaco culture.

The center also serves as the visitor center for Canyons of the Ancients National Monument . It is at 27501 Colo. 184, Dolores, about 10 miles north of Cortez (tel. 970/882-5600; www.co.blm.gov/ahc). It's open March through October daily from 9am to 5pm, November through February daily from 10am to 4pm, and closed New Year's Day, Thanksgiving, and Christmas. An admission fee of $3 for adults is charged March through October only; admission is free for those 17 and under. Allow 2 hours.

Canyons of the Ancients National Monument, CO

The 164,000-acre Canyons of the Ancients contain over 6,000 archaeological sites -- what some claim is the highest density of archaeological sites in the United States -- including the remains of villages, cliff dwellings, sweat lodges, and petroglyphs at from 700 to perhaps as much as 10,000 years old.

The primary excavated site is Lowry Pueblo, a prehistoric village about 27 miles west of Cortez via U.S. 491, on C.R. CC, 9 miles west of Pleasant View. This pueblo, which was built about 1060 and likely abandoned by 1200, is believed to have housed about 100 people. It has standing walls from 40 rooms plus nine kivas (circular underground ceremonial chambers). A short, self-guided interpretive trail leads past a kiva and continues to the remains of a great kiva, which, at 54 feet in diameter, is among the largest ever found. Hiking is permitted throughout the monument, but hikers are asked to stay on developed trails. The area offers a picnic area, drinking water, and toilets. There is primitive, dispersed camping but no developed campsites.

Canyons of the Ancients is overseen by the Bureau of Land Management and, as yet, has no on-site visitor center or even a contact station. Those wishing to explore the monument are strongly advised to contact or, preferably, stop first at the visitor center at Anasazi Heritage Center for information, especially on current road conditions and for directions. Information is also available online at www.co.blm.gov/canm and from the welcome center in Cortez. Allow at least 2 hours.

Chaco Culture National Historical Park, NM

A stunning setting and well-preserved ruins make the long drive to Chaco Canyon worthwhile. The stark desert seems strange as a center of culture, but the ancient ancestral Puebloan people (the group here are also called Chacoans) successfully farmed and built elaborate public buildings, which connected with other Chacoan sites over a wide-ranging network of roads.

From about A.D. 850 to 1250, Chaco was the religious and economic center of the San Juan Basin, with some 2,000 to 5,000 residents living in about 400 settlements in the immediate area. Stone walls rose more than four stories high, and some are still in place today.

Chaco's decline after centuries of success coincided with a drought in the San Juan Basin between 1130 and 1180, but anthropologists still argue over why the site was abandoned. Many believe that an influx of outsiders may have brought new and troubling influences. One controversial theory maintains that cannibalism was practiced at Chaco by the ancestral Puebloans or by invaders, such as the Toltecs of Mexico. Most, however, contend that, for some reason, the Chacoan people left gradually, and today their descendants live among the region's Pueblo people.

The 9-mile Canyon Loop Drive provides easy access to six major archaeological sites -- Una Vida, Hungo Pavi, Pueblo Bonito, Chetro Ketl, Pueblo del Arroyo, and Casa Rinconada -- and self-guided trail guides are available at the trail heads and the visitor center. Once you arrive at the trail heads, a bit of walking and some hiking are required.

The key ruin is Pueblo Bonito, one of the largest prehistoric dwellings excavated in the American Southwest. It has some 800 rooms covering more than 3 acres, and you'll get good views from above along the Pueblo Alto Trail.

The park is open daily year-round. A visitor center, with a bookstore and a museum showing films on ancestral Puebloan culture, is open daily year-round 8am to 5pm, except for Thanksgiving, Christmas, and New Year's Day.

Gallo Campground, 1 mile east of the visitor center, has 49 sites, including 15 that are for tents only. Other sites can accommodate RVs up to 35 feet long. The campground has toilets, nonpotable water, but no TV hookups. It also has no shade. Drinking water is available only at the visitor center. Cost is $10 per night, first come, first served. It rarely fills, but if it does, the park service will provide information about other campgrounds in the general area.

The primary entrance is off U.S. 550 and San Juan County roads 7900 and 7950. The park service warns visitors driving regular passenger cars to not trust driving directions from some map publishers or their GPS, as they may end up lost or broken down due to the severity of the terrain.

Following are our suggestions for getting to Chaco. You will find more detailed directions at the park website. To get to Chaco from Santa Fe, take I-25 south to Bernalillo (exit 242), then U.S. 550 northwest through Cuba to mile marker 112. Turn left onto San Juan County Road 7900 for 5 miles, and turn right. Go 16 miles on San Juan County Road 7950 to the park entrance. Farmington is the nearest population center, and it's a 75-mile, 1 1/2-hour drive to the park. From Farmington, head east on U.S. 64 to Bloomfield and turn right onto U.S. 550. Three miles south of the Nageezi Trading Post (the last stop for food, gas, or lodging), turn onto San Juan County Road 7900 and proceed as above.

For information, contact Chaco Culture National Historical Park, P.O. Box 220, Nageezi, NM 87037 (tel. 505/786-7014; www.nps.gov/chcu).

Admission for up to 7 days costs $8 per vehicle or $4 per person on foot, bike, or motorcycle.

Aztec Ruins National Monument, NM

Misnamed by Anglo settlers who thought these ruins were built by the Aztec people of Mexico, this 500-room pueblo with a huge central kiva was actually the home of the ancestral Puebloans about 7 centuries ago, long before the time of the Aztecs.

You'll see the Chaco culture here, plus signs of Mesa Verde influence from a later occupation. Aztec's Great Kiva is the only completely reconstructed great kiva in existence. The circular ceremonial chamber, which was the central social and religious site for the people who lived here, is more than 40 feet in diameter, with a main floor sunken 8 feet below the surface of the surrounding ground.

Allow at least an hour to see the ruins on the self-guided trail, which is just under a half mile, and also stop in the visitor center to see the exhibits and watch the 25-minute film on the history of the prehistoric people of the area. There is no camping at the monument.

Aztec Ruins is approximately a half mile north of N.M. 516 (off U.S. 550) on Ruins Road (C.R. 2900), on the north edge of the city of Aztec, about 14 miles northeast of Farmington, New Mexico. The monument is open daily year-round except Thanksgiving, Christmas, and New Year's Day. Hours from Memorial Day weekend through Labor Day weekend are 8am to 6pm; the rest of the year, it's open daily 8am to 5pm.

For information, contact Aztec Ruins National Monument, 84 C.R. 2900, Aztec, NM 87410 (tel. 505/334-6174, ext. 230; www.nps.gov/azru). Admission for up to 7 days is $5 per person, free for children under 16.

Navajo National Monument, AZ

This national monument, deep inside the Navajo Nation, contains three of the best-preserved ancestral Puebloan cliff dwellings in the region -- Betatakin, Keet Seel, and Inscription House. You can visit both Betatakin and Keet Seel, but fragile Inscription House is closed to the public. There are also exhibits on the Navajo culture.

Stop first at the visitor center (daily year-round 8am-5:30pm from Memorial Day weekend through Labor Day weekend and 9am-5pm the rest of the year) to see the displays on the ancestral Puebloan and Navajo cultures, including artifacts from Tsegi Canyon. Several short films are shown, and a shop sells Navajo and Pueblo arts and crafts. Note: The national monument, located in the Navajo Nation, observes Daylight Saving Time, as does all of the Navajo Nation, but the rest of Arizona does not.

Betatakin, which means "ledge house" in Navajo, is the only one of the three ruins that can be seen easily, and that is from a distance on the easy 1-mile round-trip Sandal Trail. Built in a huge amphitheater-like alcove in the canyon wall, Betatakin was occupied only from 1250 to 1300, and at its peak may have housed 125 people. During the summer, a strenuous 5-mile round-trip and a very strenuous 3-mile hike to the ruin are led by rangers daily, and involve descending more than 700 feet to the floor of Tsegi Canyon and later hiking back up to the rim. The rest of the year, hikes to Betatakin are offered weekends depending on staff availability.

Keet Seel, which means "broken pieces of pottery" in Navajo, was occupied from as early as A.D. 950 until 1300, and at its peak may have housed 150 people. Twenty people a day receive permits to make the strenuous 17-mile round-trip hike to Keet Seel. The trail is open only in summer.

Other trails in the park, open year-round, are the .8-mile round-trip Aspen Trail, which branches off the Sandal Trail to drop some 300 feet into an aspen forest; and the Canyon View Trail, a .6-mile round-trip walk that offers views of Betatakin Canyon.

The free, shady Sunset View Campground has 31 small sites (RVs 28 ft. long or less), paved roads, toilets, and drinking water, and is open year-round. Another free campground, Canyon View, is open April through September and has 16 sites, dirt roads, pit toilets, but no water.

From Cortez, follow U.S. 160 south and west 137 miles into New Mexico and Arizona, to Ariz. 564, which leads north 9 miles to the monument. For information, contact Navajo National Monument, HC 71 Box 3, Tonalea, AZ 86044 (tel. 928/672-2700; www.nps.gov/nava). The park is open daily year-round. Admission is free.

Canyon de Chelly National Monument, AZ

People have lived in these deep canyons for more than 2,000 years, and there are more than 100 prehistoric dwelling sites in the area. The monument includes two major canyons -- Canyon de Chelly (which comes from the Navajo word tségi, meaning "rock canyon") and Canyon del Muerto (Spanish for "Canyon of the Dead"). The smooth sandstone walls of rich reds and yellows contrast sharply with the deep greens of corn, pasture, and cottonwood on the canyon floor.

Stop first at the visitor center (daily 8am-5pm year-round except Christmas) to see exhibits on both the present-day Navajo residents and the ancient peoples who inhabited the canyons. There's often a silversmith at the visitor center demonstrating Navajo jewelry making. Note: The national monument, located in the Navajo Nation, observes Daylight Saving Time, as does all of the Navajo Nation, but the rest of Arizona does not.

The two rim drives cover about 20 miles each and, with stops, can easily take 2 hours apiece.

The North Rim Drive overlooks Canyon del Muerto. From view points, you'll see Ledge Ruin, occupied between A.D. 1050 and 1275, and, nearby, a kiva (circular ceremonial building). Farther along, Mummy Cave -- named for two mummies found in burial urns -- is a large amphitheater with two caves, believed to have been occupied from 300 to 1300. There's a three-story structure similar to dwellings at Mesa Verde; altogether there are 80 rooms.

The South Rim Drive climbs the South Rim of Canyon de Chelly, providing views of canyons, the junction of Canyon del Muerto and Canyon de Chelly, and several ruins, including First Ruin, with 22 rooms and two kivas. Farther along is the White House Overlook. The final stop offers a spectacular view of Spider Rock, twin towers that rise 800 feet from the canyon floor.

The White House Trail, the only trail into the canyon you can take without a guide, descends 600 feet to the canyon floor, crosses Chinle Wash, and approaches the White House Ruins. Among the largest ruins in the canyon, it contains 80 rooms and was inhabited between 1040 and 1275. You're not allowed to wander off this trail, and are asked to respect the privacy of those Navajo living here. It's a 2.5-mile round-trip hike and takes about 2 hours.

Access to the floor of Canyon de Chelly is restricted. To enter the canyon, you must be accompanied by a park ranger or an authorized guide (unless you're on the White House Trail). Navajo guides will lead you into the canyon on foot or in your own or their four-wheel-drive vehicle, and there are also guided horseback tours. Check at the visitor center for fees and other details.

The shady Cottonwood Campground has 96 sites (RVs up to 40 ft. long only), a dump station, and toilets. There is water in summer only. At this writing the campground is free, but park service officials say that negotiations are under way for management of the campground to be taken over by the Navajo Nation Parks and Recreation Department, which would charge a camping fee.

To get to Canyon de Chelly from Cortez, follow U.S. 160 south and west 76 miles into Arizona to U.S. 191, which you take south 62 miles to Chinle, where you turn east to enter the park, which is open daily year-round. Admission is free.

For information, contact Canyon de Chelly National Monument, P.O. Box 588, Chinle, AZ 86503 (tel. 928/674-5500; www.nps.gov/cach).

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.