Tehran is home to many historical locations, including the royal complexes of Golestan, Sa'dabad, and Niavaran, where the two last dynasties of the former Imperial State of Iran were seated. Tehran's most famous landmarks include the Azadi Tower, a memorial built under the reign of Mohammad Reza Shah of the Pahlavi dynasty in 1971 to mark the 2,500th anniversary of the founding of the Imperial State of Iran, and the Milad Tower, the world's sixth-tallest self-supporting tower, originally planned by the Shah, completed in 2007, and the Tabiat Bridge, completed in 2014.