Wow, if we'd added all these there would be nothing but natural wonders on the map.

To add some german bias as well:
Chalk cliffs of Rügen W(more cliffs, somebody asked for it!)
Matterhorn (Not that we needed more Mountains..)
The Harz (multi tile, looks much better in reality than on wikipedia

)
Elb Sandstone Mountains
Wonders/National Wonders:
Oderburch (its one of the biggest and most important historical drainage projects in germany, started by Frederick the Great; gave him tons of additional food..

)
Walhalla Memorial (a big, aweful, cliché memorial, but historically improtant and a tourist magnet. Displays statues of important german historical figures)
Museum Island W(multiple museums stacked with art, history and other awesomeness from all over the world.)
Hamburgs Speicherstadt W(its a big medieval commerce district with unique architecture)
Sansoucci Palace and Parks W(Palace and huge Parks around it in Potsdam, build by Great Old Freddy)
W= World Heritage
All of these are very well known in Germany. Of course I know that doesn't qualify them to get included.

Im curious if this thread here will become a bigger Wonders modpack. Would be cool.