The castle of Mila lies at the north edge of the settlement Kastro, north of Mila, on a location strategically situated for the control of the plain of Ano Messenia. It is part of a series of smaller castles built in prominent sites to control the medieval routes and to assert the local authority of the Frankish feudal lords. It is identified with Chateauneuf, founded by Isabella Villehardouin (1297-1301), in order to intercept the growing invasion of the Greeks of the Despotate of the Morea. The trapezoid in plan castle has two baileys.

The inner one is reinforced by three large four-sided towers that resemble western European castle-residences. Two two-storey wings were arranged on either side of an elongated courtyard, along the castle’s long sides. On the first floor of the south wing were two large orthogonal halls, lit by large windows. The castle gate was located at the north wing, which is now mostly in ruins. The castle chapel was housed at the south-eastern side of this wing. The outer bailey extends north of the inner one, at a lower level. It was less elaborately built and reinforced by a semicircular tower in the middle of its north-eastern side. Access was provided via a gate opened roughly in the middle of the south-eastern side.