We’re taking advantage of these Heritage Days 2026 to discover the capital’s curiosities, and there are plenty! You’ll surely need more than a weekend—those September 19 and 20—to see it all, but so many museums, churches, institutions and unusual and little-known places await to share their secrets with you, through guided tours and activities, often free. This cultural showcase has some delightful surprises in store this year!
La Maison du Fontainier: one of the last underground remains of the Aqueduc Médicis in Paris
In the heart of the 14th arrondissement, the Maison du Fontainier is home to the last glimpse of the Médicis aqueduct. Listed as a historic monument, this underground vestige opens its doors only on guided tours, to discover the history of water in the capital. [Read more]
What if, after the Catacombs or the Carrière des Capucins, we stayed underground, visiting the Maison du Fontainier? It's an ideal opportunity to delve into the bowels of Paris, through thehistory of water. Built between 1619 and 1623 in the Faubourg Saint-Jacques, this ashlar house's interest lies in its relationship with the 13km-longMédicis aqueduct, of which it is the 27th and last manhole (a masonry device used to inspect an underground pipe).
The King's fountain-maker, Thomas Francine, lived here to oversee water distribution in the capital. The liquid circulating in the aqueduct arrived in the basements of this house, divided into three basins: the Carmelite basin, intended for the clergy; the King's basin, which supplied the Luxembourg palace and its fountains; and the City basin, intended for public fountains. The latter, however, had the least water!
The house, with its beautiful stone dormers, lost its function in 1870, and only became a Monument Historique in 1994.
Guided tour of the Fountain Keeper's House
Also known as the Grand Regard of the Observatory or the 27th in name, the Fontainier House was built at the request of Henry IV and later Marie de Medici to improve Paris’s water supply, with a particular focus on the Left Bank.
Linked to the so-called Medici aqueduct, it channels the groundwater from the Rungis area and its surroundings. This aqueduct, running parallel to the ancient Gallo-Roman route, begins at the Water Square (Lookout No. 1) in Rungis, reaches Paris through the current Gentilly Gate, passes beneath the Montsouris Park, crosses the Alésia-Montsouris district, the La Rochefoucauld health complex, the Observatory Park, and ends at the Fontainier House.
Built between 1613 and 1623 by contractors Jean Coing and his son-in-law Jean Gobelin, it spans nearly 13 kilometers. Its route is punctuated by 27 lookouts that allow the system to be monitored and maintained, while also aerating the water to keep it fresh. The final distribution occurs in the basements, above which, in 1619, the Fontainier House was erected in a striking Louis XIII style. It served, until the Revolution, as the official residence of the king’s chief Water and Fountain administrator. These basements are now classified as historical monuments. They are divided into three rooms, each housing a reservoir known as the King’s, the Entrepreneurs’ (Carmelites’), and the City’s.
The vaulted aqueduct opens into the central reservoir of the Entrepreneurs. From these basins, three conduits extended the water throughout Paris until the mid-19th century.
Access: Metro Port-Royal, Bus 38, 91
Participation conditions: Free of charge | No reservation required
Hours: Saturday, September 19, 2026 — 12:30 PM to 4:30 PM | Sunday, September 20, 2026 — 10:00 AM to 5:00 PM
Dates and Opening Time
From September 19, 2026 to September 20, 2026
Location
Fountain maker's house
42 Avenue de l'Observatoire
75014 Paris 14
Prices
Free
