After the death of Joseph Stalin in March 1953, the frozen American-Soviet relationship began little by little to thaw. Communist Party General Secretary Nikita Khrushchev made surprise appearances at the 4th of July receptions at Spaso House in 1954 and 1955. Vice President Richard Nixon stayed at Spaso House when he came to Moscow to open the first large-scale American National Exposition in Sokolniki Park, and dined with Khrushchev at a dinner at Spaso House hosted by Ambassador Llewellyn Thompson. The Cold War was still not over - shortly before Nixon's visit, a microphone was discovered hidden in the chandelier near Ambassador Thompson's office. Nonetheless, five thousand Soviet citizens attended events at Spaso House in 1957, more than in the previous twenty-three years.