The Marburg Building System is one of the earliest, most consistent and internationally best-known German building system. Its development marks the beginning of the doubling of the German university building stock in just 20 years. The building site at Marburg Lahnberge was possibly the most consulted example for university planning in the 1960s and 1970s. Meanwhile, the qualities of the buildings are seldom appreciated, the system’s intrinsic facility for modification, adaptation to new user requirements or extensions are not used. The architectural quality of the buildings, erected on the Lahnberge campus in Marburg, their consistent approach down to the details, the technical innovation of the serial production of building elements in an on-site field factory and the thorough planning process to standardise all building components is indeed remarkable. The underlying principle of openness bears considerable potential to prolong the lifespan of the buildings, if, as a start, the existing defects are repaired. The advantages of the buildings, their basic system and the underlying concept may not be obvious, but on closer examination, they are undeniable. They could and should be utilised.