That was pretty darn fast, my good man. My hay is off to you.
You can get non-yellowing scotch tape which can be used to line the edges to give them more strength and less likely to fray. Not so useful for the ones that slide into position though.I joke about blasphemy, but when assembling my classic card terrain for TribeMeet this year I did find a lot of it is really starting to show its age and fail. particularly the two level towers like you've done above.
It might be time to permaglue some of the buildings together.
