In the frame of the construction of the Spiegelhof building in the years 1937 to 1939, the Old town district at Petersberg was demolished. During archaeological excavations excellently preserved medieval wooden house structures (11th century) were discovered. These findings are unique for Switzerland, but they are also Europe-wide largely without parallels. The current research project that integrates archaeobiological and geoarchaeological studies on organic deposits, house structures, ash midden and activity areas will allow new insights into the early craftsmen quarter.