Citadel
The citadel enthrones high above the old town on Jakobsberg hill. Its predecessor was the Schweickhardtsburg fortress which prince-elector Johann Schweickhardt von Kronberg had built in 1620. However in 1631, Mainz was already occupied by Sweden during the Thirty Years' War.
The actual development of today's citadel, with its regular layout and the four bastions Alarm, Tacitus, Drusus and Germanikus, began in 1655 under prince-elector Johann Philipp von Schönborn. The fortress towering over Mainz did not serve its purpose for long, however, as the city did not have the money for a powerful garrison. French troops took the city in the Palatinate Succession War.
Today, the citadel is home to different municipal offices. Furthermore, the structure serves as the location for the annual nationally renowned Open Ohr Festival.
Drusus stone
In the south-west corner of the fortress the Drususstein (Drusus stone) is located - an original 30 metre tall Roman monument. It was erected in 9 AD by the Roman army in honour of the general and emperor's brother, Drusus. The general, who is considered the founder of the city of Mainz, had an accident on the way back from a military campaign on the Elbe. He succumbed to his serious injuries.