[2] The oldest part of the current castle is a 13th-century, originally free standing, residential tower.

In 1515-20 the Bishop Hugo von Hohenlandenberg rebuilt the castle to its current appearance.

The outer wall of the castle moved to stand exactly over the north-west corner of the Roman era fortress.

He built workshops around the castle building as he experimented with motors, trucks and machinery.

In 1944 his son, Hippolyt Saurer sold the castle to the city for 150,000 Swiss francs.