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Eiffel Tower – Paris
Image by Arch_Sam
The Eiffel Tower (French: La tour Eiffel, [tuʁ ɛfɛl]) is an iron lattice tower located on the Champ de Mars in Paris, France. It was named after the engineer Alexandre Gustave Eiffel, whose company designed and built the tower. Erected in 1889 as the entrance arch to the 1889 World’s Fair, it was initially criticised by some of France’s leading artists and intellectuals for its design, but has become both a global cultural icon of France and one of the most recognizable structures in the world. The tower is the tallest structure in Paris and the most-visited paid monument in the world; 6.98 million people ascended it in 2011. The tower received its 250 millionth visitor in 2010.
The tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building. Its base is square, 125 metres (410 ft) on a side. During its construction, the Eiffel Tower surpassed the Washington Monument to assume the title of the tallest man-made structure in the world, a title it held for 41 years, until the Chrysler Building in New York City was built in 1930. Because of the addition of the aerial atop the Eiffel Tower in 1957, it is now taller than the Chrysler Building by 5.2 metres (17 ft). Not including broadcast aerials, it is the second-tallest structure in France, after the Millau Viaduct.
The tower has three levels for visitors, with restaurants on the first and second. The third level observatory’s upper platform is 276 m (906 ft) above the ground, the highest accessible to the public in the European Union. Tickets can be purchased to ascend by stairs or lift (elevator) to the first and second levels. The climb from ground level to the first level is over 300 steps, as is the walk from the first to the second level. Although there are stairs to the third and highest level, these are usually closed to the public and it is generally only accessible by lift.
The design of the Eiffel Tower was originated by Maurice Koechlin and Émile Nouguier, two senior engineers who worked for the Compagnie des Établissements Eiffel, after discussion about a suitable centrepiece for the proposed 1889 Exposition Universelle, a World’s Fair which would celebrate the centennial of the French Revolution. In May 1884 Koechlin, working at home, made an outline drawing of their scheme, described by him as "a great pylon, consisting of four lattice girders standing apart at the base and coming together at the top, joined together by metal trusses at regular intervals". Initially Eiffel himself showed little enthusiasm, but he did sanction further study of the project, and the two engineers then asked Stephen Sauvestre, the head of company’s architectural department, to contribute to the design. Sauvestre added decorative arches to the base, a glass pavilion to the first level, and other embellishments. This enhanced version gained Eiffel’s support: he bought the rights to the patent on the design which Koechlin, Nougier, and Sauvestre had taken out, and the design was exhibited at the Exhibition of Decorative Arts in the autumn of 1884 under the company name. On 30 March 1885 Eiffel presented a paper on the project to the Société des Ingénieurs Civils; after discussing the technical problems and emphasising the practical uses of the tower, he finished his talk by saying that the tower would symbolise.
Work on the foundations started on 28 January 1887. Those for the east and south legs were straightforward, each leg resting on four 2 m (6.6 ft) concrete slabs, one for each of the principal girders of each leg but the other two, being closer to the river Seine, were more complicated: each slab needed two piles installed by using compressed-air caissons 15 m (49 ft) long and 6 m (20 ft) in diameter driven to a depth of 22 m (72 ft) to support the concrete slabs, which were 6 m (20 ft) thick. Each of these slabs supported a block built of limestone each with an inclined top to bear a supporting shoe for the ironwork.
Each shoe was anchored into the stonework by a pair of bolts 10 cm (4 in) in diameter and 7.5 m (25 ft) long. The foundations were complete by 30 June and the erection of the ironwork began. The very visible work on-site was complemented by the enormous amount of exacting preparatory work that was entailed: the drawing office produced 1,700 general drawings and 3,629 detailed drawings of the 18,038 different parts needed. The task of drawing the components was complicated by the complex angles involved in the design and the degree of precision required: the position of rivet holes was specified to within 0.1 mm (0.004 in) and angles worked out to one second of arc. The finished components, some already riveted together into sub-assemblies, arrived on horse-drawn carts from the factory in the nearby Parisian suburb of Levallois-Perret and were first bolted together, the bolts being replaced by rivets as construction progressed. No drilling or shaping was done on site: if any part did not fit it was sent back to the factory for alteration. In all there were 18,038 pieces joined by two and a half million rivets.
At first the legs were constructed as cantilevers but about halfway to the first level construction was paused in order to construct a substantial timber scaffold. This caused a renewal of the concerns about the structural soundness of the project, and sensational headlines such as "Eiffel Suicide!" and "Gustave Eiffel has gone mad: he has been confined in an Asylum" appeared in the popular press. At this stage a small "creeper" crane was installed in each leg, designed to move up the tower as construction progressed and making use of the guides for the lifts which were to be fitted in each leg. The critical stage of joining the four legs at the first level was complete by the end of March 1888. Although the metalwork had been prepared with the utmost precision, provision had been made to carry out small adjustments in order to precisely align the legs: hydraulic jacks were fitted to the shoes at the base of each leg, each capable of exerting a force of 800 tonnes, and in addition the legs had been intentionally constructed at a slightly steeper angle than necessary, being supported by sandboxes on the scaffold. Although construction involved 300 on-site employees, only one person died thanks to Eiffel’s stringent safety precautions and use of movable stagings, guard-rails, and screens.
Equipping the Tower with adequate and safe passenger lifts was a major concern of the government commission overseeing the Exposition. Although some visitors could be expected to climb to the first or even the second stage, the main means of ascent clearly had to be lifts.
Constructing lifts to reach the first platform was relatively straightforward: the legs of the lower section were wide enough and so nearly straight that they could contain a straight track, and a contract was given to the French company Roux, Combaluzier and Lepape for two lifts to be fitted in the east and west legs. Roux, Combaluzier and Lepape used a pair of endless chains with rigid, articulated links to which the car was attached. Lead weights on some links of the chains’ upper or return sections counterbalanced most of the car’s weight. The car was pushed up by the links below, not drawn by those above: to prevent the chain buckling it was enclosed in a conduit. At the bottom of the run the chains passed around 3.9 m (12 ft 10 in) diameter sprockets. Smaller sprockets at the top guided the chains.
The puddled iron (wrought iron) structure of the Eiffel Tower weighs 7,300 tonnes, while the entire structure, including non-metal components, is approximately 10,000 tonnes. As a demonstration of the economy of design, if the 7,300 tonnes of the metal structure were melted down it would fill the 125-metre-square base to a depth of only 6.25 cm (2.5 in), assuming the density of the metal to be 7.8 tonnes per cubic metre. Additionally, a cubic box surrounding the tower (324m x 125m x 125m) would contain 6,200 tonnes of air, almost as much as the iron itself. Depending on the ambient temperature, the top of the tower may shift away from the sun by up to 18 cm (7.1 in) because of thermal expansion of the metal on the side facing the sun.
At the time the tower was built many people were shocked by its daring shape. Eiffel was accused of trying to create something artistic without regard to engineering. However, Eiffel and his engineers, as experienced bridge builders, understood the importance of wind forces and knew that if they were going to build the tallest structure in the world they had to be certain it would withstand them. In an interview with the newspaper Le Temps (Paris) of 14 February 1887, Eiffel said:
Now to what phenomenon did I give primary concern in designing the Tower? It was wind resistance. Well then! I hold that the curvature of the monument’s four outer edges, which is as mathematical calculation dictated it should be … will give a great impression of strength and beauty, for it will reveal to the eyes of the observer the boldness of the design as a whole.
Maintenance of the tower includes applying 50 to 60 tonnes (49 to 59 long tons; 55 to 66 short tons) of paint every seven years to protect it from rust. The height of the Eiffel Tower varies by 15 cm (5.9 in) due to temperature.
The nearest Paris Métro station is Bir-Hakeim and the nearest RER station is Champ de Mars-Tour Eiffel. The tower itself is located at the intersection of the quai Branly and the Pont d’Iéna.
More than 250 million people have visited the tower since its construction in 1889: in 2012 there were 6,180,000 visitors. The tower is the most-visited paid monument in the world. An average of 25,000 people ascend the tower every day which can cause long queues. Tickets can be purchased online to avoid long queues.
The tower has two restaurants: Le 58 tour Eiffel, on the first floors and the Le Jules Verne, a gourmet restaurant on the second floor, with a private lift. This restaurant has one star in the Michelin Red Guide. It is run by the multi-Michelin star chef Alain Ducasse and owes its name to the famous science-fiction writer Jules Verne.