Remains of a Byzantine-period church were discovered in 1992 near the Monastery of Mar Elias, when the highway between Jerusalem and Bethlehem was widened and a bulldozer accidentally uncovered and damaged a mosaic floor. In the first, limited excavations (October 1992 February 1993) only a section of the western part of the church was uncovered, revealing mosaic floors which were re-covered to ensure their preservation.

Located in an ancient olive grove within the southern municipal borders of Jerusalem, on land owned by the Greek Orthodox Patriarchate, the site is bordered in the south by a terrace with an open water reservoir, known by its Arabic name, Bir Kadismu.

Bir means water cistern or reservoir, Kadismu preserves the Greek name of the place, Kathisma, meaning "seat."

Renewed excavations in 1997 revealed a large church built in the 5th century and restored in the 6th century. In the 8th century, it was converted into a mosque, and was destroyed shortly thereafter.

The size of the building and its sophisticated, octagonal plan indicate that this was a church of great importance. Surrounding the flat, protruding rock (the "seat"), which is its focal point, were two octagonal hallways: the inner one served as a walkway (ambulatoria) from which the worshippers could view the stone seat; the outer hallway was divided into rooms and four chapels. The whole church was surrounded by a square envelope, divided into rooms with mosaic floors.

Nearly all the rooms of the church were paved in colored mosaics; some had been added in the 8th century. The mosaics are in many shades of red, yellow and green in a variety of floral and geometric designs, the small tessarae laid on a firm plaster bedding.

Among the motifs are guilloches (braided bands) interspersed with medallions of floral designs. Depicted in the corners of the southern room of the church are four cornucopiae (horns of plenty), supporting acanthus leaves from which grape tendrils emanate.

According to the 6th century "Life of Theodosius", the church and the monastery of the "Old Kathisma" were built by the wealthy widow Ikelia at the time of Juvenalis, Bishop of Jerusalem (450 458). The account indicates that the church was built on the resting-place of Mary, halfway on the road from Jerusalem to Bethlehem, and dedicated to Mary Theotokos (God bearer). Also, that St. Theodosius himself, who lived in the 5th century, was sent for training as a monk to the monastery of the "Old Kathisma". From the 12th century onwards, a water cistern in this areas was noted as a holy site; it served as a refreshment and rest station for pilgrims traveling on the Jerusalem-Bethlehem road until the end of the last century.

The site is at present covered over and not open to the public.