The foundations and basements of the Eiffel Tower

Hidden beneath the Eiffel Tower are its foundations, of course, which are firmly anchored 22.3 feet underground, but also the basements housing the technical equipment for each pillar, such as the elevator mechanisms, and offices.

The history of the foundations of the Eiffel Tower

The construction of a metal structure as tall as the Eiffel Tower required substantial work to ensure it had foundations able to withstand anything. More than 130 years later, the innovations of Gustave Eiffel’s company have proven their worth!

The choice of the location for the Tower in 1886 was directly linked to its foundations: the Tower was originally intended to be built within the 1889 World Exhibition, between Chaillot Hill and the Champ-de-Mars. However, Chaillot was not a viable location for secure foundations and it was on the banks of the Seine, in line with Pont d'Iéna, that the Tower was constructed, like a huge gateway to the World Exhibition.

The foundations (which extend to a depth of 22.3 feet below ground) were built in 1887 in just four months. On the Champ-de-Mars side, two piles were built on a 6.6-foot-deep concrete footing, itself resting on a layer of compact gravel.

Things were more complicated on the Seine side because the foundations go below the riverbed, which passes right next to the Tower. To resolve the issue, Eiffel used a technique that had previously been employed in bridge building, based on watertight metal boxes into which compressed air was injected to allow the workers to work below water level. The corners of each pillar also have their own masonry foundations measuring 16.4 by 32.8 feet, meaning that the soil only supports between 42 and 57 pounds per square inch. Thanks to its ingenious foundations, the Tower is as light as a feather despite its 8,047 tons of iron!
 

Over time, the Eiffel Tower has withstood plenty of adverse weather conditions, including floods - such as the major one in 1910 - and storms, and not once have its structural integrity and foundations been cause for concern!
 

What is in the Eiffel Tower’s basements and can they be visited?

Beneath each pillar is a basement housing technical equipment and spaces dedicated to the operation of the monument.

Underneath the East and West pillars is the fascinating machinery for the historic hydraulic elevators running from the ground to the second floor. These large basements contain the control room and equipment allowing the cabs to travel the 377 feet to the second floor at a speed of 6.56 feet per second, including counterweights, the trolley and its sets of pulleys, the pumps, and machinery.
 

These spaces are not open to the public. However, exceptional visits of the machinery in the East or West pillars are sometimes organized on certain national Heritage Days, but numbers are limited due to the confined space.
 

Under the South pillar is the machinery for the service elevator which is used solely for operations purposes at the Tower.

The basement beneath the North Pillar houses spaces such as offices and cloakrooms for the staff of the Société d'Exploitation de la Tour Eiffel (SETE), who operate the monument every day. This pillar is currently undergoing work for the renovation of the North elevator and temporary premises for the Tower’s staff have been installed on the esplanade. The North and South Pillar basements are not open to the public.

Is it true that there are hydraulic cylinders under the pillars of the Tower?

No! There is nothing of the sort under the Tower. The pillars rest on fixed and stable foundations. This enduring legend stems from the construction method used to build the Tower, which sometimes required high-precision maneuvers to align the piles and columns. Find out more on the following page: Is the Eiffel Tower mounted on cylinders?