The church is located northwest of the settlement of Kato Vassiliki in Nafpaktia, on a low spur of Varassova, in the southwestern foothills of the mountain. It is located about 2 km north of the coastal settlement, being built on a plateau overlooking the valley of Kato Vassiliki. It has an imposing structure and large size. Though now in ruins, its walls are still preserved to a considerable height.
It is a rare and transitional type of church, combining the free and the crossed-dome triconch temple forms. That is to say that in the easternmost part it follows the semi-cross-in-square, single-aisled triconch type with a three-sided apse, while in the western part it follows the type of the crossed-dome with a narthex. It is likely to have been built on an ancient building, perhaps a temple, as it has incorporated ancient material, namely dressed stone blocks, in a second use. The walls are built with semi-worked limestones, alternating with single or double courses of bricks, whilst bricks have also been used in the vertical joints. They bear decorative crosses and hold in place devices to improve the acoustics of the room.
Broadly speaking, the church lacks any decoration from moulded clay elements, except for brick arches flanking the windows, which show similarities with those of Saint Luke in Phocis. It was probably the katholikon of a monastery, a spiritual and guiding centre of the region, as the remains of the surrounding buildings show. It dates from the second half of the 10th or the first half of the 11th centuries.
