To do it well, the lens alone will be over your total budget of 1600 €. (And when you get into interchangeable lens cameras, it's usually more about the lens(es) than the camera body.)
Rule of thumb: the more glass/lenses a lens has (both inside and outside), the more expensive it is. Wide angle lenses need more glass to capture a wider field of view. Full frame lenses need more glass to cover a larger sensor with light. Add both of those together, and you get expensive pretty quickly.
If you insist on going full frame, IMO the best package that will do this decently without being crazy expensive (but likely still over your budget) is a Canon RP (and EF lens adapter) and Canon 17-40mm F4 L (because the 17-40mm is rectilinear (straight lines stay straight, for taking pics of big buildings) and the RP has an on-screen level (to help you keep the camera level, to avoid convergence, where buildings look like their leaning inwards) ).
But you'd likely be able to get results that are just as good for a lot less money if you go with an APS-C camera and a Canon 10-22mm or Tokina 11-16mm. (Full disclosure: I own a Tokina 11-16mm lens.) Or, if you're OK with manual focus (which, again, should be fine for stationary subjects like landscapes and buildings), a micro four thirds camera (some of which also have on-screen levels) and a Laowa 7.5mm. (Full disclosure: I own a Laowa 7.5mm lens.)