The baronial castle of Maenza originated as a watchtower around 1100-1200 and assumed its present appearance in 1500 by the will of Bernard I, one of the Ceccano Counts, who chose it as a residence.
The central body, rectangular in plan, was expanded with the addition of two reinforcing towers and with the enlargement of the thickness of the walls to withstand firearms.
On the third floor of the main building of the castle are the rooms St. Thomas Aquinas stayed in when he came to visit his niece Francesca in 1274, on his way to Lyons to the Ecumenical Council of Pope Gregory X. This is where the miracle of fresh herring happened, just before the Saint understood that his days were almost over and moved into the abbey of Fossanova. The room with a cross vault was entirely frescoed.
Today the castle is home to concerts of sacred and classical music, as well as festivals, exhibitions, performances, religious and civil marriages.