I collect postcards of libraries and unesco heritage sites. If you can't find those, then waterfalls and unusual bridges are good - or castles, cathedrals or stunning scenery.
I used to run a website: www.julia-chandler.co.uk Its still alive, but I haven't updated it for a while. Now my focus is on unesco: https://unescopostcardsblog.wordpress.com/
and libraries: https://carnegielegacyinengland.wordpress.com/