This proposed extension should incorporate the historicist architecture of imperial Prussia into the Straßburg WHS. The area is adjacent to the Grande-Ile, but its style is inherently different. The architecture is of monumental scale and aimed at openly demonstrating the contested Prussian rule. Some of the most significant buildings surround the Place de la Republique (formerly Kaiserplatz). The architecture reminded me of what survived from imperial Berlin and is also similar to the monumental square in Munich once proposed as a WHS.
The area can easily be accessed by foot from the historic centre of the Grande-Ile, however, most of the buildings are closed to visitors. An exception are the municipal baths, which I believe are also included.
The extension is justified by showing urban continuity across cultures as well as representing German imperial historicist architecture destroyed elsewhere. I am not sure how convincing these two arguments are. Urban continuity is probably there and the styles are certainly distinct, but on the other hand, this might affect the integrity of the WHS. European historicist architecture might not be represented in Germany, but there are already several such examples on the list from other European countries (Paris, Vienna and Budapest, among others).