The palace with its impressive polygonal ramparts is a great example of 16th century military architecture. It was built in 1542 at the behest of Cesare Alidosi and his uncle, Rizzardo.
It only took a few years to complete construction, however, due to its great financial cost it created controversy among the family.
After the death of Rizzardo, and the death of Cesare one year later, the work halted leaving the south-west and north-west ramparts incomplete.
There is disagreement amongst historians about the name of the architect who designed the manor. Bramante and Francesco da Sangallo are two of the designers that have been credited among others.
The building had to function as both a fortress and a residence. From the archives it is possible to trace the original plan of a square layout, with four angular diamond bastions, a large internal courtyard and a large moat that has now vanished.
You entered through the main door to the east, which still exists, after crossing the moat with a three-arched bridge. Towards the village, to the south, there was a beautiful garden surrounded by a high wall, described as the “garden of delights.”
Inside today, you can visit the “courtyard of the three fountains,” which get. its name from three sandstone shaped-shells fountains. It is an authentic jewel of Renaissance art with a loggia supported by three sandstone columns and frescoes painted in 1568 by the Faentine painter Giuseppe Pasini.
Under the loggia, at the top, there are 8 circular niches that housed the busts of some members of the Alidosi family, only the names and dates of which remain today.
In 1683, under Urbano VIII, Castel del Rio became part of the Papal State, after which a period of neglect began.
In 1841, the town took charge of the building now in total ruin by emphyteusis and became its sole owner in 1877.