The Murlo Castle was the main center of the episcopal fiefdom, seat of the Bishops of Siena.
The Castle is dominated at the highest point by the imposing bishop's palace, square in shape and with a sloped base, commonly called the "Palazzone". The entrance door is interesting, surmounted by a pointed stone arch, and inside, the vaulted rooms on the ground floor and the rooms with beams on the first floor are noteworthy. The palace was built by transforming and expanding the pre-existing building consisting of a 13th century tower; traces of it can be seen on the facade and especially inside on all floors. The walls surrounding the village/castle are from the same period and are still visible along almost the entire perimeter, along which there are two doors, one to the north and the other to the south/west.
Characteristic are the houses leaning against the walls, most of which were also built after the war of Siena, in which secular traces have emerged during the renovations of recent decades.
Until 1832, the seat of the Murlo Town Hall was in this Palazzina.
Currently the Bishop's Palace houses the Archaeological Museum of Murlo, with the rich archaeological finds of Poggio Civitate; beautiful views that can be seen from the windows of the top floor.