The settlement (Aricia
in Roman times and Saricia, Aritie in the 12th century) is
located at the confluence of two hills. The castle occupies the eastern side,
perched on a rocky ridge overhanging the valley. Part of the ridge is
incorporated in the walls of the foundation escarpment. The castle has an
enceinte with two circular towers (a third one is barely recognisable) and a
cylindrical central tower. The perimeter of the structure is triangular. The Di
Capua family palace was gradually constructed around it (work was executed in
1285 by order of Bartholomew I ; in 1515 Bartholomew re-fortified the palace,
adding a cannon port and building a new enceinte). However, it was destroyed
during the uprising of 1799. The Medieval keep is naturally defensible due to
its topographical location, which is improved by some installations designed for
dropping missiles, especially the line of murder holes set on projecting stone brackets. The
keep has a basement and rises three storeys above ground level ; the entrance is
raised from the ground. The masonry is characterised by rough-cut stones of
various sizes laid on fairly regular substructures using mortar and numerous
stone shims.