The best things I have seen (and all relative to where my mind was at the time, etc.) on no basis than my own subjective taste based on the breathtaking factor.
1) Golden Temple - India (way better than the Taj Mahal, IMHO)
2) Machu Pichu - Peru
3) La Sagrada - Barcelona
I'm sure I'm forgetting something, but those are close to my top 3. Rome is cool, but I can't think of anything in Rome topping out one of those 3.