15 Interesting Things About Paris You Probably Didn’t Know

Some interesting things about Paris you probably didn’t know: the Palais Garnier opera house sits on a huge underground water tank, the Eiffel Tower was meant to be dismantled in 1909, the Paris Metro has ghost stations, and in 2025 Parisians could swim in the Seine for the first time since 1923. Here are 15 lesser-known facts about the French capital.

Paris is one of the most visited cities in the world, yet most travellers only see the postcard side of it. Behind the famous landmarks are odd rules, hidden spaces and stories that even many locals do not know. We have checked and updated this list for 2026.

Quick facts about Paris

Fact	Detail
Eiffel Tower height	330 m including the antenna added in 2022
Notre-Dame reopened	7 December 2024, after the 2019 fire
Seine swimming	Reopened to the public on 5 July 2025
Luxor Obelisk	Over 3,000 years old, erected in Paris in 1836
Rungis Market	Opened in 1969, covers 232 hectares

15 interesting things about Paris you probably didn’t know

1. The opera house sits above a giant water tank

When work began on the Palais Garnier in 1861, builders hit unexpectedly high groundwater. Architect Charles Garnier designed a double foundation with a large concrete cistern under the stage, which eased pressure on the walls and could serve as a reservoir in case of fire.

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A legend grew that the opera was built over an underground lake. Gaston Leroux used that idea in his 1910 novel The Phantom of the Opera, which is set in the building.

2. The Metro has ghost stations

Paris has several Metro stations that are closed or were never opened to passengers. Arsenal, Champ de Mars and Croix-Rouge closed in 1939 and were shut for good after 1946. Haxo was built in 1921 but has never carried a passenger.

Porte Molitor’s tracks are used to park trains, and a platform at Porte des Lilas is used for film and advertising shoots.

3. Notre-Dame’s great bell weighs about 13 tonnes

Emmanuel, the largest bell of Notre-Dame, weighs about 13,000 kg according to official figures. It was cast in 1686 and hangs in the south tower. It survived the 2019 fire, and the cathedral reopened on 7 December 2024.

4. The Concorde obelisk once worked as a giant sundial

The Luxor Obelisk in Place de la Concorde was carved for Luxor Temple in Egypt more than 3,000 years ago. Egypt’s ruler Muhammad Ali Pasha gave it to France in 1830, and it was erected in Paris in 1836.

For the millennium, brass discs and markings were laid around it in 1999 so that the obelisk worked as the pointer of a sundial. They stayed until the end of 2000. Its gold-leaf cap was added in 1998.

5. Paris once had only one stop sign

Paris relies mostly on traffic lights and the “priority to the right” rule rather than stop signs. The city’s best-known single STOP sign, near a port on the Seine, was reported to have been replaced in 2012.

6. The Eiffel Tower lifts were cut during the occupation

When German forces occupied Paris in 1940, the French cut the tower’s lift cables, and the lifts were not repaired until 1946. Hitler visited Paris that year but did not go up the tower. In 1944 he ordered it destroyed, but the military governor did not carry out the order.

7. A cannon once fired at noon

In the Palais Royal gardens, a clockmaker named Rousseau set up a small cannon that fired at noon on sunny days. Parisians used it to set their watches, a tradition remembered in the city’s lore of “bursting noon”.

8. The Eiffel Tower was not meant to last

The tower was built as the centrepiece of the 1889 World’s Fair, marking 100 years since the French Revolution. Under the original agreement it was due to be dismantled in 1909. It was spared because it proved useful for radio communication.

It now stands 330 m tall, including a digital radio antenna added in March 2022.

9. The French army still keeps carrier pigeons

The French army is said to be the only one in Europe that still keeps trained military pigeons. They are housed at Mont-Valérien with the 8th Transmissions Regiment.

10. You can swim in the Seine again

Swimming in the Seine was banned in 1923 because of pollution. After a clean-up costing about 1.4 billion euros before the 2024 Olympics, Paris opened three public swimming sites on 5 July 2025, including one at Bras Marie and one near the Eiffel Tower.

11. The city keeps a record of its trees

Paris keeps a detailed record of its trees, each one documented. The original version of this article put the count at around 470,000 trees, each tracked by the city.

12. An old trousers rule stayed on the books until 2013

A 19th-century rule required women in Paris to get police permission to wear trousers. It was officially overturned only in 2013.

13. Guillotine marks remain in the road

In the 11th arrondissement, markings set in the road show where a guillotine once stood. It was used for nearly 200 public executions.

14. Rungis is one of the world’s largest food markets

The Rungis International Market opened in 1969 when the wholesale market moved out of Les Halles in central Paris. It covers 232 hectares and handles about 1.7 million tonnes of produce a year. Wikipedia lists it as the second largest wholesale food market in the world, after Mexico City’s Central de Abasto.

15. Paris syndrome is a real condition

Paris syndrome describes a strong sense of shock some visitors feel when the city does not match their expectations. It was named by Japanese psychiatrist Hiroaki Ota in the 1980s. Reported symptoms include anxiety, dizziness and, in rare cases, hallucinations. Japanese tourists are the group most often linked to it.

Planning a trip to Paris

Many of these places can be seen in a day: the Palais Garnier, Place de la Concorde, the Palais Royal gardens and Notre-Dame are all central. Read more trip ideas in our travel section and other trivia in infotainment.

Further reading: Paris.

Frequently asked questions

Sources: Wikipedia: Eiffel Tower, Wikipedia: Palais Garnier, Khaleej Times, Wikipedia: Rungis.