When you want to find info about something visual, you could do a Google search - in this case, you could search for “cathedral”, but better to use some of the info in the introduction, like, it’s a Gothic cathedral - and, you could add “Italian” if you wanted. If you just search for “gothic cathedral”, you’d get the results shown below:

Of the image results shown, the one at upper right (Duomo di Milano) looks quite a bit like the original “what cathedral is this” picture - and, of course, Milan is in Italy! To be certain, you could do a search on “Duomo di Milano”, maybe also selecting the “Images” search mode shown under the search box (circled in red) in the screen capture above.

But if you have a “source picture”, as in this case, a more specific way of searching is to use Google’s reverse image search on a computer or on a phone. This is really powerful - it’s worth learning how to do it!