Just outside of downtown Denver, Red Rocks Amphitheater is the only naturally-occurring acoustically perfect amphitheater in the world. Since it first opened in 1941, it has been home to iconic music performances, from opera to rock. The stage is flanked by two 300-foot orange sandstone monoliths, like sails in the sky. During the day, fitness junkies run up and down the 69 rows of seats. If this is a feat you'd like to tackle, just make sure to take precautions since you'll be at 6,450 feet above sea level. There are also hiking and biking trails nearby where you can discover some of the flora and fauna of this uniquely situated park where the Great Plains meet the Rocky Mountains.
Red Rocks Amphitheatre doubles during the day as a public park, part of a larger natural rock formation with hiking trails and views. Masochists run the stairs for exercise. But in the evenings during the summer, the seats fill with thousands of music lovers who have come to see their favorite band play the famous natural amphitheater. Also look for their "Film on the Rocks" movie series in the summer.