Hoover dam should be on the list.
The Acropolis
Alhambra
Angkor
Chichen Itza
Christ Redeemer
The Colosseum
Easter Island Statues
Eiffel Tower
Great Wall of China
Hagia Sophia
Kiyomizu Temple
The Kremlin / St. Basil
Machu Picchu
Neuschwanstein Castle
Petra
Statue of Liberty
Stonehenge
Sydney Opera House
Taj Mahal
Timbuktu