St. Mary’s basilica is a three-nave church of square ground plan whose lateral walls have been preserved almost to their original height. The size of the church (11 x 24 m) indicates a large population of the nearby Byzantine castrum erecting this edifice in the 5th/6th centuries.

The altar area is two steps higher and is divided from the church nave by a partly preserved triumphal arch. The altar basis is preserved in situ. The atrium of the basilica holds a small collection of stone monuments, exhibiting, among other, church finds, transennae, stone window grids.

The specificity of St. Mary's basilica is in the appearance of the sanctuary ending with a rectangular apse, while most of the basilicas of that period had a semicircularly organized sanctuary.

In the open front part of the basilica and around it was an Early Christian cemetery 300 m long, stretching as far as the southeastern corner of the castrum.