Thuringia
Jena has good transport connections all over the state of Thuringia, but also beyond to Saxony and Saxony-Anhalt. It's just an hour from Leipzig on the ICE, a couple of hours from the GDR museum piece of Chemnitz, and has regional trains to whisk you to little gems like Weimar and Naumburg. Like many towns in this region it makes for a very convenient base for exploring.

Inter shop tower
Jen-Tower, Jena
A "brick" beside the main square