premise: Built for the Pisani doges in 1756, with 200 rooms, Tiepolo frescoes in the ballroom, and vast park with pond, labyrinth, and stables, it was purchased by Napoleon in 1807 and subsequently hosted Tsars, Hapsburg emperors, and, for their first meeting in 1934, Hitler and Mussolini.
hypothesis: A 1756 building was purchased by Napoleon in 1807.