Antique Key to the HILL Mansion Safe of the Historical Henry Walter Livingston Estate Mansion near Hudson New York. In 1794, Livingston was commended to General Washington, then the President of the United States, and was twice elected to Congress. The HILL was built about 1799. The Tag confirms one of the subsequent owners of the Livingston Estate as the founders of Otis Elevator Company. A piece of history. 4 1/2 made of heavy metal.