The Zeppelin Field is one of those areas that were left to decay.
Originally the whole backside with the speaker’s tribune ended in a gigantic colonnade. The building was modeled after the antique Pergamon Altar, only - you guess it - much bigger and wider. The columns were demolished decades ago, because they would have collapsed anyway.
Therefore the building today is far from what it was, but it is still impressive to climb up the stairs to the speaker’s tribune.