Heiligenstadt was first settled more than 5000 years ago. Traces of Roman settlement have also been found. In 1872, remains of a wall were found in Heiligenstadt that prove that a Roman tower, part of the limes once stood in this area. A Roman cemetery has also been found near the Jakobskirche (St. James’ Church), as has an Avar tomb from the 6th century. The Franks followed, settling in Heiligenstadt for the first time around 900. Originally, settlement centred on the area around the modern-day Pfarrplatz and included the first church in the area. The inhabitants were farmers who were largely reliant on their own produce. They also caught crabs and fish in the western arm of the Danube (where today the Heiligenstädter Straße is located). Wine was produced for sale; wine cellars can to this day be found in the side of the hill beside the Heiligenstädter Straße. The Klosterneuburg Monastery owned vineyards in Heiligenstadt as early as 1250. In 1304, bishop Weinhardt von Passau gave the monastery the right to take over the parish Heiligenstadt after the death of the parish priest. In the Middle Ages, Heiligenstadt was one of the richer settlements in the area. A school is documented in 1318; it was probably the only one in the area. Like many other towns on the outskirts of Vienna, Heiligenstadt suffered greatly in the turmoils of the 15th and 16th centuries. Matthias Corvinus laid waste to Heiligenstadt in 1484, while Turkish plundering during the first siege of Vienna in 1529 greatly damaged the Jakobskirche and the Michaelskirche (St. Michael's Church). It was however possible to restore the latter in 1534 thanks to donations made by the inhabitants of Döbling, Grinzing, Nußdorf and Heiligenstadt (all of which belonged to this parish).