The Eiffel Tower: How an Iron Experiment Became the Symbol of Paris

A Tower Built for a World's Fair

In 1889, Paris hosted the Exposition Universelle, a world's fair marking one hundred years since the start of the French Revolution. The French government wanted a spectacular centrepiece that would show off the country's industrial skill to millions of visitors from around the globe. A competition was announced, and more than a hundred proposals were submitted. The winner was a daring plan from the company of engineer Gustave Eiffel: an open iron tower 300 metres tall, almost twice the height of any structure built by humans until then.

The tower was placed on the Champ de Mars, a large open space beside the river Seine that had once been used as a military parade ground. It also served as the grand entrance arch to the fair. Today it stands at one end of a long park, facing the Trocadéro across the river, and it has become one of the most recognisable buildings on Earth.

Who Really Designed the Eiffel Tower?

Although the tower carries Gustave Eiffel's name, the first idea did not come from him. In 1884 two senior engineers in his company, Maurice Koechlin and Émile Nouguier, sketched a tall pylon made of four lattice girders that met at the top. Eiffel was not very enthusiastic at first. The company's head of architecture, Stephen Sauvestre, then reworked the design: he added the decorative arches at the base, a glass pavilion on the first level and other details that made the structure look more elegant.

Eiffel liked the improved version. He bought the rights to the patent from Koechlin and Nouguier and threw the full weight of his reputation behind the project. He was already famous for daring iron structures, such as the Garabit railway viaduct in southern France and the internal iron skeleton that holds up the Statue of Liberty in New York. That experience convinced the organisers that his firm could really build something so tall.

Building a Giant in Two Years

Work on the foundations began on 28 January 1887. The tower stands on four huge legs, and each leg rests on its own concrete foundation. Two of the legs are close to the Seine, where the ground is soft and wet, so workers used watertight metal boxes called caissons, filled with compressed air, to dig below the water level without flooding.

A Giant Kit of Parts

The most impressive part of the construction happened far from the Champ de Mars. In Eiffel's workshops at Levallois-Perret, on the edge of Paris, engineers produced thousands of detailed drawings, and every one of the 18,038 iron pieces was cut and drilled in advance with great precision. The pieces were delivered to the site ready to fit together like a giant construction kit. They were first held with temporary bolts and then fixed permanently with about 2.5 million rivets. Each rivet was heated until it glowed, placed in its hole and hammered flat, so that it gripped the metal tightly as it cooled.

Getting the Legs to Meet

The four legs lean inwards and had to meet perfectly at the first platform, about 57 metres above the ground. To make this possible, the builders placed hydraulic jacks and boxes of sand under the feet of the legs. By adjusting them by tiny amounts, they could tilt each leg until all four lined up exactly. Wooden scaffolding and temporary towers supported the legs while they were still leaning out into empty space.

Between 150 and 300 workers were on the site at any one time. The work was dangerous, high above the city, but it moved remarkably fast. On 31 March 1889, a little over two years after the work began, Gustave Eiffel climbed to the top and raised the French flag. The tower opened to visitors in May 1889, and nearly two million people went up during the fair alone.

Key Facts and Figures

• Original height: about 300 metres, or about 312 metres including the flagpole in 1889. New antennas added over the decades have raised it; since 2022 it has measured about 330 metres.
• Tallest in the world: it was the tallest human-made structure on Earth for about 41 years, until the Chrysler Building in New York overtook it in 1930.
• Weight: the iron structure weighs about 7,300 tonnes, and the whole tower, with lifts, shops and other fittings, about 10,000 tonnes.
• Base: the four legs stand at the corners of a square about 125 metres on each side.
• Levels: visitors can reach three levels, at roughly 57 metres, 115 metres and 276 metres above the ground.
• Material: wrought iron, specifically a type called puddled iron, which was strong, reliable and resistant to cracking.
• Visitors: it welcomes around six to seven million people a year, making it one of the most visited paid monuments in the world.

The Science Behind the Shape

The tower's elegant curving outline is not just decoration. Its shape comes mainly from one engineering problem: wind. For a very tall, narrow structure, the force of the wind is a much greater danger than its own weight. Eiffel and his engineers calculated the shape of the legs so that the wind pushing on the tower would be carried down safely into the foundations.

The lattice design is just as clever. Instead of solid walls, the tower is made of an open web of girders and cross-bracing. This lets the wind blow straight through it, while the triangles formed by the iron bars make the structure very stiff. The result is a tower that uses surprisingly little material for its size. A famous comparison says that if all the iron were melted down and spread over the square base, it would form a layer only a few centimetres thick.

A Tower That Moves

Iron expands when it is heated and shrinks when it cools. On a hot, sunny day, the side of the tower facing the sun warms up more than the shaded side, so the top bends very slightly away from the sun. Changes in temperature can also make the tower's height vary by around 15 centimetres between a cold winter and a hot summer. In strong winds, the top sways only a few centimetres, which shows how stable the design is.

From Hated Eyesore to Beloved Icon

Not everyone welcomed the tower. In February 1887, while it was still being built, a group of well-known artists and writers published a protest letter in the newspaper Le Temps. Among the signers were the architect of the Paris Opera, Charles Garnier, the writer Guy de Maupassant, the playwright Alexandre Dumas the younger and the composer Charles Gounod. They called the planned tower useless and monstrous and claimed it would spoil the beauty of Paris. A well-known story says that Maupassant later often ate lunch in the tower's restaurant, because it was the one place in Paris from which he could not see the tower.

Eiffel answered his critics calmly. He argued that a structure built according to the true laws of strength and engineering could have its own kind of beauty. The public seemed to agree: the tower was a huge success at the fair, and over time even many former critics came to accept it.

Saved by Science and Radio

Eiffel's company had a permit to keep the tower for only 20 years. After that, in 1909, ownership would pass to the city of Paris, which could have pulled it down. Eiffel worked hard to prove that the tower was useful, not just a giant ornament.

He turned it into an outdoor laboratory. Instruments for studying the weather were installed, and Eiffel carried out experiments on air resistance by dropping objects along cables from the second level. He later built a wind tunnel near the base of the tower to study how air flows around shapes, research that helped the early development of aircraft. Most important of all, he encouraged experiments with wireless telegraphy, an early form of radio.

The tower turned out to be an excellent antenna. The French army began using it for long-distance radio communication, and its value for the military was a major reason the permit was renewed. During the First World War, the radio station on the tower intercepted enemy messages, which helped the French army. Later, the tower carried radio and then television transmitters, and it still holds broadcasting antennas today.

Lesser-Known Details

72 Names of Scientists

Just below the first platform, on all four sides of the tower, Eiffel had the names of 72 French scientists, engineers and mathematicians engraved in large gold letters. They include figures such as the physicist André-Marie Ampère, the chemist Antoine Lavoisier and the mathematician Joseph Fourier. Eiffel wanted to honour the people whose discoveries made a structure like his possible. The list has one notable gap: it contains no women, even though mathematicians such as Sophie Germain had made important contributions to the science of elasticity, which is essential for building in metal.

Eiffel's Private Apartment

Near the top of the tower, Eiffel kept a small private apartment where he could work and receive guests. One of his most famous visitors was the American inventor Thomas Edison, who came in 1889 during the World's Fair. The apartment can still be seen by visitors today, with wax figures of Eiffel and Edison inside.

Paint and Colour

To protect the iron from rust, the tower must be repainted regularly, roughly every seven years. Each new coat needs around 60 tonnes of paint, and the work is done by hand by teams of painters using brushes. The tower has not always looked the same: over its history it has been painted in several shades, from a reddish brown in its early years to yellowish and bronze-brown tones. It is also painted slightly darker at the bottom and lighter at the top, so that it looks evenly coloured against the sky.

Lifts, Stairs and Lights

From the beginning, the tower had lifts, which were a modern wonder in 1889. Some of the lift machinery installed in 1899 is still in use after more than a century of upgrades and careful maintenance. Visitors who prefer to walk can climb more than 600 steps to reach the second level. At night, the tower is lit up, and since the year 2000 thousands of flashing lights make it sparkle for a few minutes at the start of every hour after dark.

The Man Who Sold the Eiffel Tower

In 1925, a con artist named Victor Lustig pretended to be a government official and told scrap-metal dealers that the city planned to demolish the tower. He managed to persuade one of them to pay him for the right to take the iron, then escaped with the money. It remains one of the most famous swindles in history.

Why the Eiffel Tower Matters

The Eiffel Tower proved that iron and careful mathematical design could reach heights that had seemed impossible. It showed the power of prefabrication, precise drawings and teamwork, ideas that later shaped the building of skyscrapers, bridges and transmission towers around the world. It also changed how people thought about beauty in architecture, showing that a structure designed openly around its engineering could be admired as art.

Since 1991, the tower has been part of the UNESCO World Heritage Site that protects the banks of the Seine in Paris. More than a century after it was meant to be taken down, it is the best-known symbol of Paris and of France, copied in souvenirs, films and smaller replicas around the world. A temporary experiment built for a single fair has become a permanent landmark, and a reminder of what curiosity, science and bold ideas can achieve.