This five-storey palace is laid out about a round courtyard. Inside, a fine spiral staircase, designed by Vignola, is supported by 30 double columns and decorated with grotesques and landscapes painted by Antonio Tempesta. The 16C paintings that embellish several rooms in the palace, by Taddeo and Federico Zuccari, as well as Bertoja, constitute one of the final manifestations of the refined and sophisticated Mannerism that is characteristic of the late Italian Renaissance.