Each Sunday and holiday certain main streets of Bogotá, Cali, Medellín, and Colombian other municipalities, are blocked off to cars for the exclusive use of runners, skaters, and bicyclists. At the same time, stages are set up in city parks. Aerobics instructors, yoga teachers and musicians lead people through various performances. Bogotá's weekly ciclovías are used by approximately 2 million people (30% of citizens) on over 120 km of carfree streets.[1]