DB Tower, lower level. A work shop and office of some type at one time. Complete with the requisite "comfy chair".
This is an oddly built tower, as it has no access to the lower level other than by the stairs. The lower level is partially underground. Ground level is approximately at the window level. There were three windows, one on each wall except the one on the left. It was also odd that the upstairs level contained relays and radio, but no area for a tower operator to work - no windows, no view.
The outside photo shows the building to have a chimney, but I saw no flue, stove, or furnace anywhere.
More photos here from the DB Tower & Bridge set.