Construction Theories There are two theories about the construction of the Meersburg castle. The first is that the Merovingian king Dagobert I, built the Dagobertturms (Dagobert's Tower), the central keep of the Meersburg, in 630. The second theory is that the castle was built in the early 12th Century, and based on the name of the tower an association with the earlier merovingian king was created. It is based on the observation that in the Lake Constance region there are no records of any castles being founded in the 7th Century, but in the 12th Century to early 13th Century many castles were built in the region.The Merdesburch Castle was first mentioned in 1113, which implies a construction date before the early 12th Century.