3508 PROSPECT STREET NW Thought to be designed by William Thornton, the architect of the U.S. Capitol, and long considered one of the most architecturally and historically significant properties in the city of Washington, Prospect House was built between 1787 and 1793 and sits high above the Potomac River at 3508 Prospect Street in Georgetown. This red brick Georgian-Federal house has been a show place for politicians and statesmen since Revolutionary War days, and is sited on nearly half an acre of beautifully manicured formal English gardens.  Among many renowned owners over the years, the property was the home of the first Secretary of Defense, James V. Forrestal, and during the Truman Administration Prospect House served as The White House Guest House for visiting dignitaries. Presidents Washington and Adams, the Marquis de Lafayette, the Shah of Iran, the President of France, and the poet Robert Frost have all been guests of Prospect House. The first floor of this 9, 000+ square foot residence includes 12-foot ceilings; a formal entrance hall; a double parlor living room with twin Adams fireplaces, a Jefferson window, and a bay window overlooking the gardens; a banquet-sized dining room with a fireplace and river views; a gallery hall; an ample-sized eat-in kitchen,  a powder room and a veranda.  Upstairs are 7 large bedrooms -- several with river views -- a sitting room and 5 full baths. A lovely library opening to the garden, a home office,  an 8th bedroom and a full bath make up the lower level.  The property includes a 41-foot swimming pool and an octagonal watch tower where one of the early owners watched his boats come into Georgetown Harbor.  A three-car garage and additional parking for 3 cars complete this extraordinary offering. Prospect House has been well-maintained and improved by its current owners, who, in the last few years, have replaced the roof; the plumbing, heating and air conditioning systems; and rebuilt all of the windows.