The Eiffel Tower was built from 1887 to 1889 by French engineer Gustave Eiffel, whose company specialized in building metal frameworks and structures. Gustave Eiffel is at the origin of many metallic works in Europe including the Porto Viaduct (Portugal), the Viaduct du Garabit (France) and the Budapest train station (Hungary).
Gustave Eiffel's company, that was located in Levallois Perret, very near Paris, France, also built the metal framework for another world-famous monument: the Statue of Liberty (New York, United States), designed by Auguste Bartholdi and offered to the United States as a gift from France to celebrate the 100th anniversary of the American Declaration of Independence in 1886.
The Eiffel Tower is made of iron, not steel. The puddle iron that makes up the Eiffel Tower's structure came from the Pompey forges (East of France). The iron plates and beams produced through the puddling process were then preassembled in the Eiffel factories in Levallois Perret using rivets.
Finally, these pieces where taken to the Eiffel Tower construction site to be mounted. The prefab system is what allowed them to build the Eiffel Tower in a record time of 2 years, 2 months and 5 days.
The iron used to build the Eiffel Tower went through a refining process called puddling which eliminated the excess carbon when the ore was melted. Following this process, you obtain almost pure iron, which was, according to Gustave Eiffel at that time, the best and most robust of materials.
To protect it from corrosion, the iron is covered with a thick coat of paint that has to be renewed every 7 years. This repainting schedule was recommended by Gustave Eiffel himself and is still respected to date.
The Eiffel Tower was built to be one the main attractions at the Paris World's Fair in 1889. That year, the World's Fair covered the entire Champ de Mars in Paris and its focus was the vast constructions in iron and steel that were the great industrial advancement of that time.
First called the 300-meter Tower, it soon took the name of the man who built it, Gustave Eiffel. The Tower opened to the public the same day as the World's Fair, on May 15, 1889.
Controversy over the Tower raged in the art world before and during its construction, but thanks to the audacity of its architecture and design, visitors and Parisians immediately fell under its charm and more than 2 million people toured it in the first year.