The Azadi tower dominates the Azadi square which lies very close to Mehrabad airport in the west of Tehran. The Azadi tower was completed in 1971 based on a design of the architect Hossein Amanat to commemorate the 2500th anniversary of the Persian empire. It was built with white marble from the Isfahan region. At night the tower is illuminated with lights which change their colour every 5-10 seconds.