The Eiffel tower

The assembly of the 1887, and supports began on July 1 was completed twenty-two months later.
All the elements were prepared in the factory at Levallois-Perret on the outskirts of Paris, where Eiffel's company was located. Each of the 18 000 pieces used in the Tower was designed and calculated, traced out to an accuracy of a tenth of a millimetre and then put together, in pieces of around five metres each. Between 150 and 300 workers on the building site, led by a team of veterans of the great metal viaduct projects, were responsible for assembling this gigantic meccano set. Equipping the Tower with elevators able to carry many people in perfect safety posed a difficult technical problem.Nobody had ever built one to climb so high and under such conditions. All the original elevators have now been replaced. The elevators installed in the East and West legs by the French company Roux, Combaluzier and Lepape,went up to the first level.They were driven by a double looped chain, powered by hydraulics. In 1897 they were replaced by elevators built by Fives-Lille, which were in turn modernized in 1987. The equipment supplied by the American company Otis to reach the second level comprized a cabin with an upper and lower deck, mounted on sloping runners and pulled by a cable that was powered by a hydraulic piston. The elevator on the South leg was removed in 1900, and replaced in 1983 by an elevator to serve customers of the "Jules Verne" restaurant. The one on the North leg was replaced in 1912 by an electric elevator, which was modernized in 1995.The vertical elevator, built by Edoux, consisted of two counterbalancing cabins.The upper cabin was powered by a hydraulic piston with a stroke of 78 metres, while the lower cabin provided the counterbalance. It was therefore necessary to change cabins half way up. Water tanks placed within the two stories of the tower created the hydraulic power required. This lift, which could not operate during the winter months, was replaced in 1983.