It was presumed that this Gothic building in Aragonese style was the birthplace of Pope Martino V. However, stylistically the palace is dated at least twenty years after the death of the Pope, with traceable patterns from the Kingdom of Naples, where he had close ties to the Colonna family. Most likely, it was home of a noble courtier, given the undeniable elegance of precious mullioned windows with pointed arches in tuff with spiral columns, adorned with carvings in the rosette, an arched portal, dentil cornices, friezes and foliage.
The building consists of three floors and a basement used as a cellar. The ground floor has two rooms; the one situated on the right side is a kitchen while the other one was likely to be used for the management of the company. At the bottom of the atrium there is a single ramp stone staircase, enhanced by two half columns, topped with capitals that support the round arch. The upper floor consists of a reception hall, decorated with a fireplace, which leads to a room, perhaps the bedroom of the owner.The top floor, probably used by the family, has on the west side a service environment and a loggia that comes out on the stairwell. Formerly owned by the Apolloni family, the so-called “Uditorato” building was the seat of the Court Baron.
In 1910 the palace was purchased by Cardinal Vincenzo Vannutelli who commissioned the restoration to the Giovenale architect, who based his principle of restoration on the reconstruction of the building through the reproduction of original features.
Fine examples of mullioned windows can be also found in other buildings overlooking the main street of the village, including the most important, right in front of the palace Apolloni itself.