Built on the site of the ancient palace of the Colonna, it was renovated between 1637 and 1647 by expanding through the purchase of some adjoining houses. Ducal palace of Genzano is the central axis of the Olmate. The façade has three rows of windows and resembles the Palazzo Barberini in Rome, while the portal, with two columns surmounted by a balcony, takes after Palazzo Chigi of Bernini. The interior is decorated with landscapes and views of the same building seen in a panorama of the town. In the 1800s a wonderful romantic English garden was created sloping down to the shores of Lake Nemi.