Once a bustling Danish port, Christiansted's careful preservation of its ornate 17th-and 18th-century buildings has made it a popular stop for visitors interested in more than a beach vacation. About six blocks of the town, the island's largest with all of 2,555 residents, is now a national historic site. The best way to explore the area is on foot, so stop first at the visitors center on Company Street for a walking guide. (The office is open weekdays 8 am-5 pm.) Start at Kings Wharf, the heart of the historic district, and then stroll nearby streets admiring the steep-roofed colonial buildings that are painted in shades of pink and yellow. The best-preserved fort in the U.S. Virgins, Fort Christiansvaern, is an impressive, muted yellow structure on the waterfront. It has dungeons, ramparts and old cannons as well as an informative museum. Open daily. Small admission fee. Other buildings of note include the Danish Customs House and Post Office -- built in 1734, it now houses the National Park Service offices. Government House, a lovely 1700s town house, was once the office of the island's governor. The Steeple Building, built by the Danes in 1733, was originally a Lutheran church. The building now contains a museum with exhibits on St. Croix's original inhabitants, local architecture and archaeology. The museum also details the early life of Alexander Hamilton, who was born on the island. At Market Square you'll find bustling produce stands on Wednesday and Saturday mornings -- it's a good place to sample local fruits and vegetables. There are plenty of nearby shops as well. The little St. Croix Aquarium showcases local marine life. A discovery room with interactive displays and a petting tank allow children of all ages to touch the sea life. Across the bay from Christiansted is Protestant Cay, where there's a small resort with a good beach and a cozy restaurant and bar that are open to the public.