Because it was sunday, virtually nothing was open before 10:00, so we started by going to Rally Grounds walk around Dokumentationszentrum, and arrived there at 09:00 to do a one hour walk around the grounds. To be honest, outside of the Zeppelin Field, the rest of the walk was a bit boring, there isn't really much left to see today outside of that, and the amphitheatre that the Dokumentationszentrum is in:

we arrived at 09:00, 1H before it opened, so we took the time to walk around the grounds

overview of the grounds, including parts that were never built due to lack of funds/time after WWII started

A huge street meant for marching and displays between monuments

Congress Hall, the only monument that almost got fully built (some were planned and never started). It was supposed to get a roof though, but that didn't happen

another view

Zeppelin Field was used for huge Nazi rallys

very big

now it's an overgrown field used for sports

part of the outside of the field is actually used as a race track a few times a year, with grand stands

A bit after 10:00 when Dokumentationszentrum opened, with did the tour with the audio guide:

A bit after 2H for the visit, we took a bus back to downtown for a city walk

Saint Sebaldus Church

Männleinaufen

Lorenz church

the church, like most of the city, was heavily damaged by WWII bombing and a lot was rebuilt

Hauptmarkt

We were supposed to do a 14:30 guided tour of bunker tunnels were a lot of art was stored to be protected from bombings, but it was run badly by a company that didn't really care, and we got incomplete information which ended up with us showing up early and being told there were no spots left for the only tour of the day that's maybe in English (or not). Instead, we just had a quick walk up to Kaiserburg, the Imperial Castle, which we just had a quick look at without going in.
The city view from there was a bit underwhelming, sadly, the view was a bit underwhelming:

So, since it was close to 15:00, we opted for doing to the Deutsches Museum, a great museum that happens to contain a church inside of it (!). I barely got to see all of it in 3H, and at normal pace, it's likely worth most of a day. It has a very varied collections, from caveman artifacts, to middle ages, to church history, to science instruments, musical instruments, old paintings, new paintings and art, nouveau art, and more:

nice faucets

I then went to the church inside the museum

how many museums have a church inside of them?

We then had dinner in downtown and want to get some sleep due to an early train to Dresden the next morning