In an ancient city filed with lots of oldest this and oldest that, the Palace of the Governors, on the north side of Santa Fe's plaza, is the granddaddy of them all. It was build in 1610 as the original capital of the Spanish colony of New Mexico, making it the oldest continually occupied public building in the U.S. Today it's part of the New Mexico History Museum complex, which includes the Museum of New Mexico Press, the Fray Angélico Chávez History Library, and extensive photo archives. As you can imagine, the palace's 15,000-object collection spans centuries, including everything from conquistador helmets and native hide paintings to a stagecoach and a clock hit by a bullet during Pancho Villa's raid on Columbus, New Mexico in 1916. The building itself is a historical artifact, having been the seat of four distinct regional governments—Spain, Mexico, the Confederacy, and the Territory of New Mexico—and under the rule of no fewer than 100 governors. (Glass panels in the floor reveal ongoing excavations.) Visitors who are overwhelmed by all this history can catch free docent-led tours daily. Outside, under the palace's distinctive portal, registered Native American vendors sell jewelry, pottery, and more, all of which has met strict quality controls. You can see the highlights in about an hour, but if you're interested in history this place could fill days.