The Circuito Interior Bicentenario ("Bicentennial Inner Loop") or more commonly, Circuito Interior or even more simply Circuito, is a 42-km-long (26 mi) urban freeway (in parts) and at-grade boulevard (in others), forming a loop around the central neighborhoods of Mexico City. It was built starting in 1961.[1] The Circuito Interior received the appellation Bicentenario (Bicentennial) after a renovation that took place in 2010, Mexico's bicentennial year.