The byzantine monastery of Ellinika or Palaiokastro is located in Antheia, northwest of Kalamata. The katholikon is dedicated to Koimisi Theotokou (Assumption of Mary). It is a domed two-column, cross-in-square church, lacking a narthex and with the rare feature of an arcosolium (arched recess) at the outer north-western corner. A bell tower, synchronous with the church, rises at the southern end of the west wall. The cloisonné masonry consists of large-sized blocks and randomly picked brick fragments, judging by their uneven thickness.

The ceramoplastic decoration is rather plain, however, certain details in some places (dome, arch window) attest to a remarkable level of stone-cutting. This observation, combined with the existence of a platform, leads to a dating in the 12th – 13th centuries. Despite the church’s good state of preservation, some of its architectural features have been altered. The striking wall paintings are of a slightly later date than the construction of the church.