The castle stands on top of a rocky hill, northeast of Kato Melpeia, in a site that supervises the plain of Ano (upper) Messenia and the mountain pass towards Arcadia. In the Chronicle of the Morea it is mentioned by the name Dimandra, in the late 13th century. The name Krebeni was introduced for the first time in the archives of the Florentine family of bankers, the Acciauioli in 1354. The castle’s shape is almost triangular, following the contour lines. The hill is steep on all sides but the north-eastern. No traces of the entrance gate have been located. The castle consists of two baileys, with two building phases.

The outer bailey occupied the eastern side of the rock and the north wing is defined by a straight section of the wall, with traces of an ancient fortification at its base. Two gun loops are opened on the wall face, formed on the inside as blind arches, perhaps to support the parapet above. The curtain wall is interrupted by a square tower, whose masonry is characterised by the a large number of bricks used; a room in its ground floor was possibly a cistern. The remaining sides of the outer bailey were probably not walled, being protected by the steep rock itself. Within it remains are visible of ruined buildings of uncertain use. The inner bailey was occupying the north-western top of the rock, on a higher level. Wall remains can be seen only on the northern, weaker, side. A square donjon is situated at its northern part, and at the southeast a large rectangular building and an ovoid cistern.