The Georgetown House Tour — the 83rd on April 27 — could not have asked for a more beautiful Saturday. Nine homes were on the tour, which began in 1931. It is the oldest in the nation and the programs of St. John’s Episcopal Church on O Street. Organizers estimated that a least 1,200 persons had gone on the tour. It was a busy Saturday in Georgetown. Besides checking out some beautiful houses, visitors and neighbors may have also spied the likes of Conan O’Brien and Psy who were in town for the White House Correspondents’ Association dinner on Saturday. O’Brien was seen walking along P Street.