Nearly 10 million people visited the 1876 Centennial Exposition, the first American World's Fair, mounted in West Fairmount Park.Nicholas Wainwright, Russell Weigley, and Edwin Wolf II, eds., Philadelphia: A 300-Year History, (W.W. Norton & Company, 1982), pp. 467-68. In his Centennial guidebook, Thompson Westcott went further than Watson, presenting (what he thought was) documentary evidence that the Letitia Street House was "the oldest house in Philadelphia," and had been "the first house which was built in the city."Thompson Westcott, "Penn's Mansion, Letitia Court," The Official Guide Book to Philadelphia, (Philadelphia: Porter & Coates, 1875), pp. 321-22. Westcott expanded on this case in his next book, arguing that the house's construction "must have been commenced before Penn's arrival [in 1682]."Thompson Westcott, "Penn's Cottage," The Historic Mansions and Buildings of Philadelphia, (Philadelphia: Porter & Coates, 1877), p. 14. It was well documented that Penn had rented the Slate Roof House as his city residence during the 1699-1701 second visit — John Penn was born there. But despite that building's direct associations with the Penn family and Pennsylvania's colonial government, and despite desperate calls by antiquarians to preserve it, the Slate Roof House was demolished in 1867. Every other building associated with Penn, including his country house, also had been demolished. As the two-hundredth anniversary of Pennsylvania's 1682 founding approached, there was a desire to honor Penn with a monument. The Letitia Street House became that monument.
