Rebecca Gore used their exposure to European country estates to design a lavish new building for their Waltham estate during their English sojourn . Designed with the assistance of French architect Joseph @-@ Guillaume Legrand and probably also influenced by the works of English architect Sir John Soane , the house that was built upon their return to the United States in 1804 ( now known as Gore Place ) is one of the finest extant examples of Federalist architecture .