https://en.wikipedia.org/wiki/Bernardo_Bellotto
I found info about this painting on the website of Hamburger Kunsthalle: https://online-sammlung.hamburger-kunsthalle.de/en/objekt/HK-645/idealvedute-mit-palasttreppe
If I understand correctly this is not an existing place, but an imagined staircase, even though Bellotto’s paintings were realistic representations of actual buildings and cities.
This is part of a series by Adam Hillman where he recreated famous paintings from everyday objects, here is an article about them: https://mymodernmet.com/famous-paintings-arrangements-adam-hillman/
This is definitely Guernica, and it seems like it’s painted on some kind of biscuits?