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.