The Palace of Vicars that was built around the XVI century, when it was restructured to become the base of the Vicariate's judicial administration, can be admired inside the Medicean Castle.
With the arrival of Florentines in 1406, the "Vicarius Laris et Collinarum", a wide judicial organization divided into three town halls, namely Lari, Crespina and Rosignano, was instituted. Its base, the Medicean Castle of Lari, was chosen also to stop the power that Bishop of Pisa still wanted to exercise on the territories recently annexed to Florence, even if he had always been the owner of the complex. The Vicar was sorted out every six months among the Florentine citizens and he was sent to Lari for six months. Once he arrived in the village, he had to got to the Palace of Vicars. His main duties are to administer justice and organize military defences against possible aggressors.
The palace, as we see it today, was created in the XVI century after the building activities that the Florentines carried out aimed at reinforcing the castle and creating a recognizable structure that could be used as an administrative centre. In effect, above the entrance, the emblems of the Medici stands out and it symbolizes the dominion of the family and of Florence in the Pisan countryside.
Nevertheless, it is known that the Pisan countryside perceived a rental fee for the castle at least until the second half of the XVIII century. The precious Della Robbia earthenware also decorate the late XVI-century fašade and they represent the emblems of the Vicars' families who followed one another in the palace.
During the whole XVII century, the Palace of the Vicars still had a "Room of tortures" that was even frescoed, once. In this room condemned people usually endured corporal tortures, but in 1594 also the famous trial to Gostanza da Libbiano of Bagni di Cascina was carried out here. She was a young girl accused of witchcraft who confessed her presumed relationship with the devil right in this room of the palace. This woman was led to San Miniato and she was freed after she took back what she had said and thanks to the arrival of a more benevolent inquisitor.
On the ground floor the, Court room can still be visited. On the first floor, there are the apartments of the Vicar and the People's room decorated with many frescoed emblems. During the period of the Lorraine these rooms were the privileged places of the Grand Dukes to admire the wonderful landscape surrounding the castle.