For many the defining symbol of Paris, the Eiffel tower was built as a temporary structure for an international exhibition in 1889. Other building built on the Champs de Mars for this and similar exhibitions were demolished. Designed by Gustav Eiffel, a bridge builder, the tower is around 300 metres tall and has viewing platforms at several levels. The tower weighs over 7,000 tons, has 12,000 metal sections and 2,500,000 rivets.