I've had two on this trip we are doing -- Edinburgh when I emerged from the underground train station, and the whole Mont Blanc experience, including the ride in a cable car up a sheer cliff face.
The first time I saw the Canadian Rockies, I had the same feeling.
I almost couldn't believe what I was seeing or doing in each case. I stood there in amazement.
These moments don't come along that often, and I though it would be a good thread for cycling tourists to post those breathtaking experiences (not just sights) they've had.
For the purposes of this thread, don't restrict it to your bicycle tours; post whether it's been on other travels as well (because if it was worth it then, it might be worth us cycling there to see or do it, too).