Well, the other buildings (mmm, maybe I should say "edifices", since they're not all buildings) nominated with the Opera House are the Eiffel Tower, the Statue of Liberty, the Colosseum, the Taj Mahal, Stonehenge, the Pyramids, the Acropolis, the Great Wall of China, Cambodia's Angkor Wat, the Machu Picchu Temple in Peru, the Easter Island statues, and the Kremlin.
(I'm not sure if this is all of the shortlisted wonders - apparently there were 77 originally nominated (this time round - there's been an attempted selection of new wonders before this)). The Pyramids are the only wonder remaining from the original 7 listed in 200BC).
There's a bit more information
here.