A king falls ill in 1744 and promises a saint a church. It takes twenty years to lay the first stone and a quarter-century more to finish. By the time the scaffolding comes down the king is dead, his grandson's throne is shaking, and the church is about to become something nobody planned: a temple for the ashes of philosophers.
The vow, and the building
In 1744 Louis XV fell gravely ill at Metz and vowed that if he recovered he would rebuild the crumbling abbey church of Saint Geneviève, Paris's patron saint. He recovered, and laid the first stone himself twenty years later, in 1764.
Jacques-Germain Soufflot designed it: a neoclassical building roughly 110 metres long, 84 wide and 83 high, with a crypt beneath of the same footprint. It stands at the top of the Montagne Sainte-Geneviève, the highest point of the Left Bank's old centre — ground that has been sacred since the Middle Ages.
It was built between 1764 and 1790, and turned into a Panthéon in 1791. Its function then changed at least six times in the following century — church, tomb, church again — until the Third Republic fixed it as a secular mausoleum in 1885.
The pediment reads Aux grands hommes la patrie reconnaissante: to great men, the grateful nation.
Come and see the Earth turn
In 1851 Léon Foucault hung a 67-metre wire beneath the dome with a bob that scratched a trace in sand on the floor. The line of the swing shifted, hour after hour, because the building was turning underneath it.
His invitations to scientists carried the line: "You are invited to come and see the Earth turn."
The experiment was stopped by Louis-Napoléon's coup in December 1851. A pendulum swings under the dome again today — though it is a copy. The original is in the Musée des Arts et Métiers.
Being honoured here is not permanent
Mirabeau, the first great man admitted in 1791, was thrown out in 1794 after documents revealed his secret correspondence with the king. Marat entered in 1794 and was removed in 1795.
Under Napoleon the crypt filled with senators, marshals and officials, many of them now entirely obscure — including several Italians and a Dutch admiral. Soufflot himself was brought into the crypt in 1829: the architect is buried in his own building.
Recent entries include Joséphine Baker (2021), Missak and Mélinée Manouchian (2024), Robert Badinter (2025), and the historian Marc Bloch with his wife Simonne (2026).
Eight things almost everyone believes that aren't true
| Claim | Verdict | What is actually the case |
|---|---|---|
| It was built as a temple to great men | False | It was built as a church for Saint Geneviève, on Louis XV's vow, and converted in 1791 |
| Everyone honoured in the Panthéon is buried there | False | Several are cenotaphs or symbolic coffins, including Baker and Badinter, Moulin's presumed ashes, and earth for de Gaulle-Anthonioz and Tillion |
| Voltaire's bones were stolen and dumped in 1814 | False | A long-running rumour, disproved when the coffin was opened in 1897 |
| Marie Curie was the first woman in the Panthéon | Partly false | First on her own merits, in 1995. Sophie Berthelot entered in 1907, beside her husband |
| Foucault invented the pendulum experiment here | Partly false | He ran it first in his cellar, then at the Paris Observatory, and only then publicly here in 1851 |
| The pendulum you see is Foucault's original | False | It is a copy. The original is at the Musée des Arts et Métiers |
| It is a copy of Rome's Pantheon | False | It borrows the name and the portico idea. The plan, dome and structure are different |
| Saint Geneviève defeated Attila | Legend | Tradition says she urged Parisians to stay and pray, and Attila turned away. There was no battle at Paris |
Two smaller things
A church financed partly by lottery: the state's coffers were empty, and a lottery helped pay for Louis XV's vow.
And in 1908, at the ceremony transferring Zola's remains, a journalist fired a gun at Alfred Dreyfus and wounded him in the arm. The Panthéon is where France argues with itself about who it admires, and occasionally the argument has been literal.
Hear this one standing in front of it
Wanderlight's Paris guide covers 14 landmarks and runs 3 hr 55 min in total. It plays offline, keeps going with the screen off, and doesn't ask you to make an account.
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Written from Wanderlight's research dossier for Panthéon — the same one the narration is written from. Where the evidence is thin, this page says so rather than rounding the uncertainty up.