I stayed for a week at Schloß Reinhardsbrunn, on the Thüringer Waldbahn from Gotha, in 1977 deep in the DDR era.
You can also reach it from Fröttstädt via the Friedrichroda branch off the main line.
I think it's closed now, but it was the place where Prince Albert and Victoria first met.
http://en.wikipedia.org/wiki/Reinhardsbrunn
During my stay, I visited Erfurt, Weimar and Jena (behind a steam loco, the last time I had one on a normal public service) and Eisenach.
Two good excursions were to the top of the Großer Inselsberg (on the Rennsteig long distance path), and to the Wartburg above Eisenach.
The funny bit about the finger post on top of the Inselsberg was that all the fingers pointing to West Germany were missing.
It was a radio station and no doubt broadcasting propaganda or jamming the western equivalent.
You can walk up through the woods from the Tabarz terminus of the tram.
I had a dodgy moment on the branch train, when I couldn't remember the name of the junction on the main line.
I got the attention of a bunch of schoolkids as I tried to recall the name "Fröttstädt" for the guard.
I thought I was about to be hauled off to the Stasi HQ for fare evasion, but they all just laughed at the stupid foreigner!
On another train I found myself sat opposite a Soviet army officer in full regalia, but luckily he didn't want to chat.
I passed through on a train again 3 years ago, and was amazed how "normal" the area now was.
The formidable rail frontier at Gerstungen is no more, of course.
The main line railway has a very interesting history.
http://en.wikipedia.org/wiki/Halle–Bebra_railway
