Iron is the main metal in the Eiffel Tower's original wrought-iron structure. The tower was assembled from puddled iron, a refined form of wrought iron, rather than modern structural steel. Its components were manufactured at the Compagnie des établissements Eiffel works in Levallois-Perret and assembled in Paris.
Gustave Eiffel's company designed the tower for the 1889 Exposition Universelle, held to celebrate the centenary of the French Revolution. Construction began in 1887, and the tower was completed in 1889. About 18,000 individual iron parts were joined with roughly 2.5 million rivets.
The open lattice design reduced wind resistance while providing strength and allowing the structure to rise to an unprecedented height. The tower reached about 300 metres at completion, excluding later antennas, and was the world's tallest man-made structure until New York's Chrysler Building surpassed it in 1930.
It is often casually called a steel tower, but its original structural material is wrought iron. Regular painting protects the iron from corrosion and has also changed the tower's color over the decades.