Some 15,000 African slaves were buried in a Manhattan graveyard in the 17th and 18th centuries, but their final resting places were lost to memory until 1991 when construction workers stumbled upon human remains during renovations of a federal building. The site is now considered one of the most important archeological finds in the United States. In 2006, a handsome, symbol-laden National Monument (operated by the National Parks Service) was dedicated by poet Maya Angelou and Mayor Michael Bloomberg. A visit to the African Burial Ground, and the small museum that’s attached, should take no more than half an hour, but it’s a worthy pilgrimage, uncovering, as it does, a part of American history that is too often brushed to the side.