The veneration of St. Thomas at this particular spot was already present in the 6th century. A church and a school were built there in the 9th century. They burned down because lightning struck them in 1007 and again in 1144. A very large church built like a fortress to resist fires better was started in the year of 1196. Building works were interrupted several times, until they finished with building side-chapels in Gothic style. In 1524 the church became Lutheran. Today, it is in charge of several schools. There is also a seminary (A special school for priests) in the baroque building next to it. 