During excavations in the Cathedral Square (Domplatz) in the 1980s, two concentric moats were discovered. They were probably parts of a fortification. Neither traces of the inner building nor additional protection like rampart or palisade could be found. Carbon dating and typical pottery shards give evidence for believing that the fortification was established in the 7th century and pulled down around the year 800. Thus, the fort seemed much too old for the Hammaburg, which was mentioned in documents of the 9th century. However, new excavations in 2005/06 showed that the inner moat is older than the outside moat. So there are two successive fortifications. The older one was built in the 8th century and leveled around 800. This fortification, here called Hammaburg I, may once have surrounded the courtyard of a family of Saxon elite. There were probably commercial and residential buildings next to this courtyard. The fortification laid on a strategically ideal hill in the Geest in the river delta between Alster and Elbe.