The palace, built on a steep slope, appears with the curious shape of a boat with the bow heading towards the Mario Theodoli corso along which it overtakes the arched loggia.
The palace has this complex structure as a result of the numerous extensions that have occurred since the end of the thirteenth century.
Tradition has it that in the castle of San Vito in 1368 by Oddone Colonna was born, who became Pope Martin V in 1417, and the birth room has been converted into a private chapel by Gerolamo Theodoli in the eighteenth century.
It was with the Marquis Alfonso and his brother Mario Theodoli, cardinal in 1643, that the structure of the castle and the town changed radically. They smoothed out the rough ground and gave rise to long and comfortable road that took the name of Borgo Mario Theodoli.