Aquileia is one of those perfect Italian sites. This tiny village of just over 3,000 souls was once a major Roman city and early Christian stronghold, with a rich heritage that has left it littered with ruins and some of the best paleo-Christian mosaics in Europe. The Roman colony was founded in 181 B.C. and witnessed such momentous ancient events as Emperor Augustus's meeting with King Herod of Judea in A.D. 10, the murders of would-be Emperor Maximinus (by his own army) and Emperor Constantine II (by his brother), and the sacks of Attila the Hun in 452.
Remains of the Roman colony are open sites (open 8:30am to an hour before sunset; free admission), some still being excavated, that lie scattered north of the current town. Just to the north of the main Piazza Capitolo, behind the tourist office, are a set of Roman houses and Christian oratories with excellent floor mosaics. From here, walk right (east) a bit to turn north up Via Sacra alongside the river, which leads to the remains of the Roman harbor. Turn left on Via Gemina then left again on Via Giulia Augusta to pass, on the right, a stretch of ancient road and, on the left, a row of standing columns marking one edge of the Forum (among the items displayed here, look for the Gorgon's head). The road forks at the Grande Mausoleo, a 1st-century-A.D. tomb hauled here from the edge of town. The right fork (Via XXIV Maggio) will lead you past the remaining scraps of the amphitheater and baths (still being excavated).
The left fork (really straight on down Via Giulio Augusto) takes you in a few blocks to Via Roma and the Museo Archeologico (tel. 0431-91-016 or 0431-91-035), which houses some nice statuary, mosaics, bronzes, and glassware, plus the excellently preserved hull of a Roman ship. Admission to the museum is 4€ for adults, 2€ for E.U. citizens ages 18 to 25, and free for those younger than 18 and older than 65; it's open Monday 8:30am to 2pm, Tuesday to Sunday 8:30am to 7:30pm (open to 11pm on Sat June-Sept). The last admission is half an hour before closing.
Christianity is also ancient in Aquileia. A major church council called here in 381 was attended by such towering early theologians as saints Jerome and Ambrose. The fabulously mosaic-filled Basilica on Piazza Capitolo (tel. 0431-919-719) is precisely as old as the official church in Italy, founded in A.D. 313, the same year Emperor Constantine declared Christianity to be the state religion. In the early 20th century, the church's original 4th-century mosaic floor was uncovered to reveal a colorful cornucopia of early Christian iconography mixed with pagan symbols and portraits of 4th-century congregants spreading over 700 sq. m (7,535 sq. ft.). The basilica was substantially rebuilt in the early 11th century, when the now-faded apse frescoes were painted. In the chapel, to the left of the altar, is a bas-relief, from 1170, of Christ with St. Peter and the freshly martyred St. Thomas of Canterbury. Later frescoes also litter the church, including some lovely Byzantine 12th-century ones in the main crypt.
The Cripta Affreschi is entered next to the medieval reconstruction of the Holy Sepulcher at the entrance end of the basilica's left aisle. The mosaics here hail from three eras: Augustan ones from a Roman house (just to the left), an early-4th-century floor laid at the same time as the Basilica's (this was once a neighboring church), and later-4th-century ones as well. Admission to the Basilica is free, though the Cripta charges a fee (some years it is tied into the Museo Archeologico ticket); both are open daily from 9am to 5pm (until 6pm on Sat and Sun). April to October, they are open from 9am to 7pm. Admission is 3€ for adults and free for children younger than 10.
Aquileia lies on local road 352 (take the Palmanova exit from the A4) some 11km (6 3/4 miles) inland from Grado, a low-key Venice Lido-like semi-island resort where Aquileia's population, and fortunes, moved to escape Dark Ages barbarian raids by the likes of Huns and Lombards. The easiest way here without your own wheels is the bus from Udine to Grado, though you can also catch a bus here from the Cervignano del Friuli train station 8km (5 miles) to the north on the Trieste-Venice line.
Aquileia's tourist office is on the main Piazza Capitolo (tel. 0431-91-087 or 0431-919-491; www.aquileia.net).