The Morris-Jumel Mansion, New York City

A former Revolutionary War headquarters, the house was bought in 1810 by French wine merchant Stephen Jumel and his American-born wife. In 1964, a group of visiting schoolchildren said they were "shushed" by a woman in a filmy violet dress - presumably Madame Jumel. "Subsequent curators have been told to downplay the ghosts, out of fear that rowdy elements might want to be difficult on Halloween."