There are so many others that I can't decide for just one and thus won't use this option.
Concerning the Leaning tower of Pisa: it should have never made it into the game without the cathedral it belongs to. It is, after all, just the tower bell tower of one of the most wonderful cathedrals. Sure, the tower is more famous than the cathedral itself - but it's just a weird thing to include this way. Big Ben is, while named like that, also the Houses of Parliament in civ VI. Come to think of it, it's actually a joke that we've never had a real Italian cathedral (sistine chapel obviously doesn't count as that).