There is a twelfth-century church in the third arrondissement where two of the pioneers’ aeroplanes hang in place of the altar, and a pendulum swings under the vault to prove that the Earth turns. The Musée des Arts et Métiers is the oldest industrial and technical collection in the world, and it has occupied the priory of Saint-Martin-des-Champs ever since the Revolution nationalised it and handed it over to a school.
Work out the cost before you leave the house, because here it changes a great deal from one visitor to the next: if you are under 26 and live in the European Union, you go in free, the first Sunday of the month is free for everyone, and the Paris Museum Pass really does cover it, which in Paris is not a given. On the other days full price costs 12 euros, and it closes on Mondays.
Why did a collection of machines end up inside a medieval church?
Let’s begin!
1. A medieval priory full of machines
How do you end up putting an aeroplane on the altar?
In November 1789 the National Assembly placed the property of the clergy at the disposal of the nation, and the priory of Saint-Martin-des-Champs stopped being a monastery. In 1794, on a proposal the abbé Grégoire put to the Convention, the Conservatoire national des arts et métiers was founded, charged with collecting machines, models and instruments and with teaching the French to build them. In 1798 the building was assigned to it, and in May 1802 the galleries opened to the public.
The museum has never changed address since. The great restoration closed it from 1994 to 1999, and it came out divided into seven sections: scientific instruments, materials, construction, communication, energy, mechanics and transport. The online catalogue holds more than 70,000 records, and the museum itself has chosen forty-two of them as unmissable. I picked the eight machines below for the same reason it is worth coming here: each one tells the moment when something changed for good.
2. Foucault’s pendulum, and the sphere that fell
In 1851 Léon Foucault hung a sphere from a long wire and let it swing. The sphere keeps moving in the same plane, but on the bed of sand beneath it the traces shift from one minute to the next. The pendulum is not turning: the floor is turning, and the floor is the Earth. Foucault tried first in the cellar of his own house, then under the dome of the Panthéon, half an hour’s walk from here.
The sphere the museum keeps is lead clad in brass, it measures twenty centimetres by seventeen and weighs 28.3 kilos. It is not alone: a second sphere, in iron, served at the Palais de l’industrie during the universal exposition of 1855, and both have been here since 1869, given by Foucault’s mother.
Now comes the part no label explains and the museum’s own site leaves out. The one you see swinging is a copy. On 6 April 2010 the cable snapped, the original sphere fell on the marble floor and was dented in several places, beyond any repair. It stayed for years in the museum’s reserves in Seine-Saint-Denis, then it came back here: you will find it in a case, next to the pendulum that works. The fact comes from the press of the time collected by Wikipédia, not from the museum, which says nothing about it.
3. Cugnot’s fardier, and the wall that may never have been there
In 1769 the military engineer Nicolas Joseph Cugnot built the first vehicle able to move without animals pulling it. A steam boiler feeds two cylinders in turn, set on either side of a single driving wheel, and a ratchet wheel, a mechanism that clocks used at the time, turns the thrust of the pistons into rotation. The same mechanism lets the fardier go in reverse as well. Follow the link between the boiler and the front wheel with your eyes, because the whole machine is there.
The one on show is the second, built between 1770 and 1771 by Michel Brézin to Cugnot’s design: seven metres twenty-five long and four tonnes of its own weight, meant to carry five more at four kilometres an hour. It entered the Conservatoire in 1799 and has not moved since: what you have in front of you is the object, not a reconstruction.
One story about it turns up everywhere: the fardier launched through the streets, the brake that fails, the wall knocked down, the first road accident in history. The account first appears in 1804, thirty-three years after the events, and no source of the time records it. In its record for the object the museum writes only that the project was abandoned in 1771, and it quotes a letter of 1779 in which the field marshal marquis de Saint-Auban grumbles about “the mania for novelties”. That letter, at least, is documented.
4. The Pascaline, and the trade it wiped out
Blaise Pascal was nineteen when he began, and he did it for his father, who at Rouen had to add up the taxes of a whole généralité by hand. Between 1642 and 1652 he built a series of arithmetic machines with toothed wheels: you turn a crank, and the carry passes from one digit to the next on its own. The museum keeps four of them, out of nine that survive in the world, and they are not all alike: the one in the photograph has eight wheels, and above the last two columns are the words sols and deniers, engraved because the machine was set for the currency and not for abstract numbers.
Look at it knowing what it stands for. Until then whoever counted was a person, and the very word we now give to machines, computer, was the name of a job. It is the first object in this museum where you watch human work pass to a device, and it will not be the last.
5. Vaucanson’s loom, and the principle that reaches us
What has an eighteenth-century loom to do with a computer?
Try to picture how a patterned cloth was woven before Jacques Vaucanson. You needed a second workman, the drawboy, sitting above the loom, who raised the right threads by hand at every pass of the shuttle. In 1746 Vaucanson built a loom that does that work on its own: a perforated cylinder turns, and the holes decide which threads rise. The pattern leaves a person’s head and hands and becomes a sequence of holes, information a machine knows how to read.
And here the story closes on itself. In January 1803 the First Consul had the Conservatoire take on a weaver from Lyon called Joseph-Marie Jacquard, with the job of keeping the machines in order; among the tasks he was given was reassembling Vaucanson’s loom, which had been found in pieces in the attics. He studied it, and between 1804 and 1805 he perfected a loom of his own: the same principle, but the cylinder becomes a chain of punched cardboard cards. Those cards reached the computers of the mid-twentieth century, and the loom Jacquard started from is this one, in this building.
6. Volta’s pile, in a room that still has its 1880s decoration
In 1799 Alessandro Volta discovered that contact between two different metals produces a current, and he piled up discs of zinc, of silver and of cardboard soaked in brine. He announced the invention on 20 March 1800, in a letter to the Royal Society in London; he showed it to Napoleon later, in November 1801, at the Institut de France, and came away with a gold medal. Until then electricity was a drawing-room affair, a spark you showed your guests; from that point on it becomes a continuous source, and with that current chemists began to separate the elements. Attention: the museum’s record squeezes the two dates into one and puts the meeting with Napoleon in 1800 as well.
The museum’s example dates from around 1800, stands sixty-eight centimetres high, weighs a little under ten kilos and arrived here in 1814. It is worth raising your eyes while you look at it: the energy room has kept the decoration installed in the 1880s, with the names of Becquerel, Savart, Fresnel and Arago on the walls. It is a museum inside the museum, and nobody tells you.
7. The pioneers’ aircraft, and the one that is not in the church
The route ends with transport, and transport ends in the church. Above your head, where the altar stood, hangs the Blériot XI, and behind it a biplane. The two aircraft that tell the story of how flight arrived, though, are not in the same room, and their own stories are opposite ones.
The Avion n° 3 by Clément Ader dates from 1897, and the museum describes it with an honest form of words: the machine with which Ader tried to lift himself a few metres. It never flew, and its inventor gave it to the Conservatoire in 1903, the same year the Wright brothers lifted off for real. Look for it where you do not expect it: it hangs above the grand staircase, and not in the nave. It was in the nave until the works of the 1990s, suspended a few metres above the cars, and from there they moved it.
The Blériot XI is the aeroplane that worked, and that one stayed in the church: in 1909 Louis Blériot crossed the Channel, and a few weeks later the aircraft was already in the museum’s galleries.
In the church, under an arch, you will also find the model of the Statue of Liberty that Bartholdi made in 1878, eight years before the real statue was unveiled in New York. From 22 September 2026 to 1 August 2027 the museum devotes an immersive experience to it, Lady Liberté, which you pay for separately and which takes the ticket up to 21 euros.
8. The dulcimer player, the automaton that breathes
In 1784 the clockmaker Pierre Kintzing and the cabinetmaker David Roentgen built a lady seated at a dulcimer, a little over fifty centimetres tall on her small table, and presented her at Versailles. She does not pretend to play, and you notice as soon as you get closer: she really strikes the strings with the hammers, she moves her head and her body, and her chest rises and falls as though she were breathing. The following year Marie Antoinette bought her and gave her to the Académie des sciences so that it could study her. Her repertoire runs to eight airs, one of which comes from Gluck’s Armide.
The museum also keeps her winding keys, the tuning key of the dulcimer and the box of spare parts, which says a good deal about how fragile she was. A few steps away, in the communication section, there is another object that is a toy and a revolution at once: the prototype of the Cinématographe by the Lumière brothers, from around 1894, built with Charles Moisson. From there on, images move.
Practical information
Details checked on 26 September 2026 on the official site arts-et-metiers.net. Prices and opening hours change: check again before you go.
Tickets. The permanent exhibition costs 12 euros full price and 9 reduced, and the reduction goes to large families and to Cnam staff. With the Lady Liberté immersive experience the ticket rises to 21 euros and to 18. The audio guide costs 5 euros. Free admission. Entry is free for the under-18s, for young people between 18 and 25 who live in the European Union, for disabled visitors and their companion, for jobseekers, teachers and journalists. On the first Sunday of the month the museum is free for everyone, the immersive experience excepted. Opening hours. The museum opens Tuesday to Sunday, from 10:00 to 18:00, and on Friday it stays open until 21:00. The desks close 45 minutes earlier and the upper floors 30 minutes earlier. Closing days. It closes on Mondays, on 1 January, 1 May and 25 December. On 24 and 31 December 2026 it closes at 16:00. Paris Museum Pass. The museum is included in the pass, together with the museum of the Institut du monde arabe. If you are planning two days of national museums, you can get the pass here. Getting there. The entrance is at 60 rue Réaumur. The stops are Arts-et-Métiers, on lines 3 and 11, and Réaumur-Sébastopol, on line 4. How long it takes. You walk the seven sections in two hours, three if you stop to read. The church on its own deserves twenty minutes, and it is worth keeping for last.
The exhibitions on at the museum, with their dates, are in the table of exhibitions in Paris.
Where to go from here
The Marais begins just outside the door, and ten minutes on foot take you to the mahJ in the hôtel de Saint-Aignan, to the Musée Carnavalet, which tells the story of Paris, and to the Musée de la Chasse et de la Nature. If the models and the full-size reproductions have won you over, the Cité de l’architecture at the Trocadéro is built on the same principle. The other Paris museum that lets you watch craftsmen at work is the Monnaie de Paris, on the quai de Conti, where the foundry has been running since the eighteenth century. And if what you are after is the rest of scientific Paris, the Grande Galerie de l’Évolution at the Jardin des Plantes and the Musée de l’Homme both belong to the Muséum national d’Histoire naturelle, and the Musée Curie occupies Marie Curie’s real laboratory.
Photo credits: nave of the church by Rilba (CC BY-SA 3.0); Foucault’s pendulum by Ewout ter Haar (CC BY 2.0); Cugnot’s fardier and Pascal’s arithmetic machine by Frédéric Bisson (CC BY 2.0); dulcimer player by Jean-Pierre Dalbéra (CC BY 2.0), from Wikimedia Commons.
