In the spring of 1779 Macpherson sold Mount Pleasant to General Benedict Arnold, of unhappy memory, whose remarkable and traitorous career is known to every American. Arnold had been placed in command of Philadelphia by Washington, following its evacuation by the British, and in acquiring the most palatial countryseat in the vicinity he gratified his fondness for display and apparently saw in it a means of retaining or increasing his influence and power. It was his marriage gift to his bride, Peggy Shippen, the daughter of Edward Shippen, a moderate Loyalist, who eventually became reconciled to the new order and was chief justice of the State from 1799 to 1805. At Mount Pleasant Arnold and his wife remained for more than a year, living extravagantly and entertaining lavishly. Arnold's financial embarrassments and bitter contentions with persistent enemies became ever more deeply involved. Here in bitterness, and not without some provocation, he conceived the dastardly plan of obtaining from Washington command of West Point, the key to the Hudson River Valley, in order that he might betray it to the British. Following the discovery of the plot and Arnold's flight to the British lines, his property was confiscated, and Mount Pleasant was leased for a short period to Baron von Steuben, after which it passed through several hands to General Jonathan Williams, of Boston, in whose family the place remained until the middle of the nineteenth century, when it was acquired by the city as a part of Fairmount Park. At Number 5442 Germantown Avenue, standing directly on the sidewalk as was often the case, and with a beautiful box-bordered garden of old-fashioned flowers about one hundred by four hundred feet along the south end, is one of the most interesting old plastered houses in Philadelphia. Well known in history, it is no less notable architecturally. In general arrangement it differs little from numerous other gable-roof structures of the vicinity, two and a half stories high with chimneys at each end and handsome pedimental dormers with round-topped windows between. It is in the excellent detail and nice proportion of the wood trim, both without and within, that this house excels. Interest focuses upon the deeply recessed doorway with its sturdy Tuscan columns and pediment, and the great, attractively paneled door. The fenestration is admirable with twenty-four-paned windows set in handsome frames with architrave casings and beautifully molded sills, the lower windows having shutters and the upper ones blinds. A notable feature is the heavy cornice with large modillions, and beneath a relatively fine-scale, double denticulated molding or Grecian fret.