Yes, South America is beautiful. The surfy seas, the cloudy mountains, the endless deserts, the deep jungles, and the cities which are situated among these landscapes.
Cusco, however, captured my heart because it is simply a beautiful city. It is surrounded by mountains, and the main square is framed by two stunning old churches. It was - by miles on the Inca trail - the prettiest city I've been to in South America.
That being said, I haven't made it to Rio yet...