From 1918 he was employed as an architect for the local authorities in Königsberg (now Kaliningrad), and from 1920 for the Deutsche Ostmesse, or Eastern Fair.
In 1944 Hopp left Königsberg and settled in Dresden, continuing his professional career in East Germany (the German Democratic Republic).
The main building of the airport at Königsberg Devau is partly in use for the Kaliningrad Sport Aviation Club.
The Park Hotel is among the few pre-war German buildings to have survived in the area surrounding the former Castle Pond (Schlossteich).
The ruin of the "Haus der Technik" was rebuilt in the late 1990s, and is currently in use as a business center.