Antelope Canyon, Navajo land, Arizona, USA. Such a well known place, and it's worth it's fame, it's simply beautiful.
But very crowded too. It was extremely hard to take pictures inside. We didn't have much time to enjoy our visit there and we only went to the Upper Canyon, but I promised myself to come back and go to the Lower one too ('cause I've seen some amazing pictures of it and I'm really eager to see it!).