The castle is located in the upper part of the town and is the nucleus around which was formed the medieval village. Since 1053 its history is linked to that of the Colonna family, and in 1200s it became an impregnable defensive fortress.
Here was born Oddone Colonna, who became pope under the name of Martin V in 1417, and who can be considered the true founder of the powerful family. With him, the castle began to take on an elegant appearance. For a brief period the castle belonged to the Borgia family who increased the fortifications.
The definitive transformation of the palace was made by Philip I Colonna in the early seventeenth century when the eastern wing was raised, the system of towers was constructed and an apartment was built with a chapel frescoed by Marzio Ganassini. The chapel is dedicated to the Colonna family from San Carlo Borromeo who was an uncle of Filippo Colonna.
Philip also produced the new spectacular entrance, the park and the delightful portico of the inner courtyard. During these works the Roman aqueduct was constructed for the arrival of water to the castle and the main fountains in the town.
In 1630 the Colonna family sold the palace of Palestrina to the Barberini and continued to beautify the palace of Genazzano.
The castle suffered heavy bombing of the RAF during the Second World War in an attempt to destroy German ovens that produced food for their troops.
Today it is the centre of social life of the town and home to the CIAC – Centre for Contemporary Art.