The archaeological tour starts at one of the most important historic sites of Hamburg: the Bischofsturm (“Bishop’s Tower”) at the Domplatz (“Cathedral Square”). The circular tower foundation from the 12th century measuring 19 meters in diameter is the oldest preserved stone building of Hamburg’s historic city center. Why the tower is named after a bishop and what the function of this enormous foundation was are things the participants learn during the about 90 minutes long guided tour beneath the streets, houses and places into the early years of Hamburg’s history. The participants gain insight into the time of medieval castle complexes that were situated between the modern town hall, the Nikolaikirche (Church of St Nikolai) and the Domplatz. The participants can enjoy the end of the tour with coffee and cake in the historical atmosphere of the Dat Backhus store that lies directly inside the show room of the historic site itself.