On the Jakobsberg, a hill just behind the south station and the Theatrum Mogontiacensium, there is a large baroque citadel from the year 1660.
Inside the citadel there are several buildings which now house city offices.
The outer walls are quite overgrown with trees and bushes in places, but you can still walk around on them.
In May 2004 a group of about fifty citizens of Mainz founded a new organization called "Initiative Zitadelle Mainz" to promote the preservation and restoration of the citadel.
Like just about any other place in Mainz and vicinity, the Citadel affords nice views of the cathedral from several different angles.