Perfect, thank you! Between the reader and the librarian, we've now tracked down Peter's residence. :D I've also probably walked right past that corner, never knowing. Looks like the building itself no longer exists, but here's a 1900 picture.

cahn, O gracious salon hostess, thank you so much for asking who Lehndorff was! I never would have went looking for his diaries if you hadn't, and selenak wouldn't have had access to at least volumes 2 and 3, even if it occurred to her to read volume 1 on her own sometime.

Truly, the alchemy is magical and DW is an earthly paradise!

I have to wonder whether any Prussian noble dared to name their kid "Franz" "Joseph" for "Theresia" during those years...

Ahahaha, well, only the ones that wanted a vacation in Magdeburg.