The da Basso Fortress, wanted by the Medici, was designed by the architect Antonio da Sangallo and built under tumultuous political upheavals. It is one of the first Italian citadels, a cyclopian building with its mighty bastions bristled by turrets, burrows, walking-paths and secret passages, but also a jewel of Renaissance architecture. It features a pentagonal plan where the human figure results perfectly subscribed in the perimeter. The castle, devoted to the S. Giovanni Baptist, at a time patron of the city, was completed in only one year, between 1533 and the 1534 d. C., when the political scene was occupied by duke Alexander and the return in power of the Medici. The façade of the mastio is covered with ashlars faceted like diamond heads with spherical stones, that recall the insignias of the Medici family. For a paradoxical destiny, in all its long history begun in 1533 with the job commissioned to Sangallo, this impregnable fortress never suffered attacks of any sort and remained intact up to our days. Currently the da Basso Fortress houses the most prestigious exhibitions in the city of Florence, from the Florence Gift Mart to the EuroCamper, from Pitti Immagine to the Borsa del Turismo Congressuale, from the Mostra Mercato Internazionale to the Prato Expo. Since 1977, the inside courtyard, surrounded by the renovated historical buildings of the Building of the Nations, the Teatrino Lorenese and the Arsenal, houses a new three stories pavillion, planned by the architect Pierluigi Spadolini. Finally let’s remember that from the 1966 flood, the Laboratori di Restauro dell'Opificio delle Pietre, is located in the buildings of the South zone.