The castle of Pidima stands on top of a very steep hill, a branch of the mountain called Palioelias at a well protected site that supervises a big part of the Messenian plain and the passes connecting Messenia and Laconia. Its foundation dates to the byzantine period, around 1300. According to historical sources it was taken over by the Venetians in 1463 and by the Ottomans in 1467. The castle has an elongated rectangular shape, following the contour lines around the hilltop. The main entrance gate was probably at the south-western corner, where there is a formation of orthogonal porch, with a square tower right next to it to the east. The remains of a smaller postern can be seen to the south outside the walls.

The wall is best preserved on the south side, built with rubble masonry; a large number of bricks have been used on the north side. Blind arches are formed at the inner face of the east side, possibly to support the parapet, much the same as in the nearby castle of Androusa. The remains of various buildings have been located inside the castle, including the ruins of a rectangular one that has been identified as the donjon (inner tower or keep), as well as two cisterns. What has survived of a small, single aisle church can be seen just north of the south postern; the church was likely dedicated to Agios Ioannis Prodromos (John the Baptist). A partially ruined, unidentified cross-vaulted church is preserved at the south side, outside the postern.