The Kalorama Citizens Association Preservation Task Force hopes to ensure that Washingtonians remain conscious of the horror that was slavery in America. Holt House, originally part of the Beall family’s “Pretty Prospect” property (before Washington was even a city), was built in the early 1800s. The land upon which the big, spooky mansion resides has changed hands several times over the years. Some of these hands belonged to merciful Quaker folk; others were attached to decidedly less morally upright citizens. The federally protected mansion’s gorgeous exterior belies the histories of some of its past residents: In the house’s bowels, the slave quarters remain chillingly intact. See for yourself when the “Holt House Walking Tour” begins at 6 p.m. Meet at the west end of Walter Pierce Park, off the 1900 block of Calvert St. NW. Free. (202) 232-6113. (Arika Casebolt)