I agree that that is an important difference as well. The Berlin Wall has a predominantly negative connotation.

Here are some proposals for Germany (some already mentioned).

Olympic Park Munich
Neuschwanstein Castle (Romantic Architecture)
Hill Fort of Otzenhausen (Celts)
Schwebebahn at Wuppertal (Much larger than Vizcaya Bridge)
Heidelberg Castle (Transformation from a Castle to a Palace)
Nördlinger Ries (Impact Crater where crater still can be seen). Barringer Crater is of course another option.
If really needed: Rothenburg ob der Tauber (Instead of Görlitz which is not the best preserved, but the best repainted historic town center. The town and its archietecture are completely unimportant)
Parteitagsgelände Nuremberg (Nazi-Architecture)
Bauernkriegspanorama (One of the largest panoramas. Larger than Panorama Mesdag. Maybe the last important building of the communist era, opened September 14th 1989 (!))
VW-Plant Wolfsburg (Automobile Industry. Much better preserved than Ford River Rouge Complex. Industrial Planning, Nazi-Architecture)
Karl-Marx-Allee and Interbau 1957. Architecture and Urbanism of Post-World War II Modernism. I think we can add Gropiusstadt and Hellersdorf-Marzahn, so that Berlin can be an example for the different attempts to establish modern housing during the 20th century.
Tempelhof Airport
Berlin Wall
Eltz Castle / Burghausen Castle (if additional castles are really needed)
Large Refracting Telescope (Potsdam) with the Einsteinturm, a major building of expressionist architecture (instead of Observatory Bergedorf). But maybe Mount Wilson Observatory is a better choice for an observatory of that time.
Bromacker, Holzmaden, Solnhofer Plattenkalk (Non-hominid fossils)

For possible serial nominations of architects:
Gropius: Glaskathedrale Amberg
Van der Rohe: New National Gallery, Weissenhofsiedlung
Gehry: Vitra Design Museum

Better than most of the newly proposed sites for the T-List.

Seeing several are on the proposed T-List, the existing T-List or a former T-List I think your statement is a bit too bold.