Fort Christian is the oldest standing structure in the US Virgin Islands and one of the most important pieces of Danish colonial architecture in the Caribbean. Built in red brick beginning in 1671, it sits on the waterfront at the eastern end of Charlotte Amalie's main street and has watched over the harbour for 350 years. The distinctive clock tower was added in the Victorian era, giving it a slightly incongruous look, but the main structure is genuinely old.
The fort houses a small museum covering the history of the Danish colony, the slave trade (St. Thomas was a major transshipment point for the Atlantic slave trade), and the 1917 American purchase. The collections are modest but the building itself is the attraction. The courtyard and lower chambers tell a complicated history that Danish colonial promotional literature sometimes glossed over: this was a place of significant human suffering as well as colonial commerce. The views from the upper ramparts across the harbour are good, and the fort is worth an hour of your time.