One of New York City’s major Colonial-era sites, the African Burial Ground was active until 1784, with as many as 15,000 free or enslaved Africans interred below ground. Though the institution of slavery was officially abolished in New York on July 4th, 1827, enslaved persons were still held in New York beyond that date. The burial ground makes up nearly six acres, and dates back to the mid-17th century. Archeologists discovered the burials in the early 1990s while digging in advance of a new federal office building’s construction. After a series of protests by Black communities and others against the mistreatment of both the buried and the larger site — and the resulting Congressional hearings — the site was designated officially as a city, state and national landmark. The proposed federal building was still constructed, but its footprint was modified to preserve the burial ground. Selected via a national competition, architect Rodney Léon’s proposal for a monument to the burial ground was completed in 2007. The burial ground is the largest known excavated African cemetery in North America.