The excavation itself is situated in the south-east part of the town of Uherské Hradiště – Sady (or Derfla) near the road to Kunovice, on so-called Sady promontory. In 1959–1963 a team led by V. Hrubý (of Moravian Regional Museum in Brno) conducted an archaeological research here and found remains of an unfortified residence of religion and power nature.

Towards the end of the 8th century, one of the first Christian missionaries arrived right here. They came from Aquilei on the Adriatic coast and from Salzburg, a little later from Passau. Probably with a consent of a local prince they built on Sady promontory a church that might have been cross-shaped on the surface with a huge square tower erected above its centre. The church was roughcast, whitewashed, the floor was covered with mortar and the roof was made of baked clay components. Apparently, this architecture became the dominant of the wide neighbourhood. Completed at the turn of the 8th and 9th century, i.e. over 30 years before the rise of Great Moravia (yr.836), the church was one of the first brick churches north of the Danube. The complex of several brick sacral constructions, built in three phases, occupied a dominant position visible from afar. The first church was built in the first third of the 9th century on the Greek-cross plan. To the north of it, a hall church with an apsis-like end was annexed in the 860 – 870s. Sometimes it is interpreted as a chapel with two side entrances and its rise corresponds with the arrival of Byzantine mission builders. Most probably as late as the last quarter of 9th century a grave chamber and a chapel were added to the northern circumferential wall of the church with a cross disposition plus a brick partition in the western church. Hence there is a possibility that the western little church served for the training of catechumen whereas the chapel with a grave chamber became the last resting place of a prominent Moravian (most likely the grave of Prince Svatopluk). To the west of the complex a baptistery was also built.

Both inside and outside the religious objects 87 mortal remains from the 9th century were found, often placed in coffins and with all kinds of alms. On the north side the churchyard was separated by two walls from a group of twelve log cabins where craftsmen with their families lived and worked. Also, there was a well. On the opposite side there stood a 36 m long and 6 m wide log construction – a gathering place and perhaps also a place for training clerics. There was a solid road running between the districts. Given the situation on the Derfla mound as well as the things found there – a lead cross with a Greek liturgical inscription, writing tools etc. – this locality is often associated with activities of Byzantine missionaries.

Based on the finds of mortal remains, the original Great Moravia burial ground from the 9th and the early 10th century was topped with a new settlement‘ s graves from 11th and 12th centuries. The chapel along with the churchyard, according to a written document from 1247 consecrated to Virgin Mary, were deserted for good in the 13th century.