Visit 16th Street Pedestrian Mall - Lined with 200 trees and 50,000 flowers, this festive, mile-long pedestrian promenade has 28 outdoor cafes and offers Denver's best people-watching. I.M. Pei designed the gray and pink granite pathway to resemble the pattern of a diamondback rattlesnake. Hop on the bus – they're free and stop on every corner. After dark, horse-drawn carriages clatter up and down the Mall.