Personally i don't agree with the original OP, it's true that there are 13 american wonders but civ4 covers nearly 6000 years of history were the last 200 years have 1/5 of the total turns in a game (marathon speed).
The last century has been the american century with american have egemony on military, economic and "cultural" (if we can call Mcdonalds,jeans and cocacola culture).
Personally i think that there are amrican wonders in civ4 that can not be replaceable by others for example instead of pentagon,wall street and hollywood what would you use cannes festival LOL, or german ministery of defence or london stock exchange?
In the last century it's normal that there are so much american wonders because there is nothing comparable in the world or in europe.
Let's be clear i'm not moved by american patriottism because i'm italian and live in Italy but in my opinion there is no bias in favour of USA a lot of posts in this threa have an antiamerican bias.
If we see european capitals there is nothing of 20th century you can call it a wonder, Rome is a beatiful city with monuments and probably should have got more "wonders" in ancient eras of CIV4 but if we see to palace built in modern times there is no palace you can call it "wonder", same discourse for other european cities.Probably London deserved more wonders considered that 18th and 19th century were English Centuries.A Big Ben for example could be a good choice.
About some american wonders i agree that they don't deserve their place.
Mount Rushmore really doesn't deserve this place considered also that it can be built with fascism so an italian or german wonder would be more appropriated.Broadway is really a shame that is a wonder i' sure a lot of us never heard about it why not introduce Olympiads instead of it?
About the others in my opinion there is no choice
Pentagon,Wall Street,Hollywood,Rock and Roll, Manhattan Project,SDI,Internet,Apollo Program, anyone can tell me anything that can substitute these wonders and can be more representative?