As promised, here is a photo of the newly renovated Römertor (roman gateway). They've just redone the roof with new wood tiles, that's why it looks nearly golden right now. The old roof had more the color of the rest of the bridge (dark brown) - I guess, in a while it'll look like that again.
Next to the gate (which was built 1902), there are still some parts of the old wall left, which was part of a Roman stronghold dating back to 364-375 AD. It was there to ward off the attacks from the Germanic tribes.