The Fortress of Sant’Angelo on Mons Spatula was founded, near the Church of St. Michael Archangelo, in the second half of the 12th century, by the powerful Roman senator Giovanni Capocci (from where the name St. Angelo in Capoccia derives). The Fortress was passed down the generations following the laws of primogeniture until 1370 when Perna Capocci married Ugo Orsini and the fief of Sant'Angelo with all its possessions became property of the Orsini family.
The last Orsini to possess it was Giordano di Napoleone and at his death (early 1500s) the Fortress was ceded to the Apostolic Camera.
Around 1590, the fief of Sant'Angelo was bought by Bartholomew and Federico Cesi, uncle and father of Federico who founded the Academia dei Lincei, thereby bringing the entire Sabine-Cornicolano territory into the family's hands.
During the second half of the 17th century, the fief of Sant'Angelo was sold to the Borghese family to pay off debts, as were all the other Cesi possessions in the area. Once a local governor had been named, they lost interest in the Fortress and in just a few years its original function as a deposit for the grain produced by the family's territories had been forgotten.