Heritage Days 2026 at Beaumont-sur-Oise Castle (95), the program

Beaumont-sur-Oise Castle opens up for Heritage Days 2026. A relic of the Middle Ages, the castle’s keep dominates the banks of the Oise and offers a splendid view of Saint-Laurent Church, to be discovered on September 19 and 20.

Ready to rediscover the stunning Francilian heritage during the 43rd edition of the Journées du Patrimoine ? Across Île-de-France, wander through castles, historic monuments, museums and other exceptional sites to soak up knowledge alongside fellow enthusiasts. Take advantage of the free activities and guided tours, notably in the Val-d'Oise, where the Château de Beaumont-sur-Oise, a relic of the Medieval era, awaits you from 19 to 20 September 2026.

But before you visit, let's take a look at the castle's history: the 7th century marked the first turning point in the evolution of this Val-d'Oise building. It was at this time that construction began on its great stone keep (37 m high). Higher than the bell tower ofSaint-Laurent church (32 m), it was used to store food on the first floor, and to house the lord's apartments upstairs. In 1223, the last Count of Beaumont died without issue, and the castle was bought by King Louis VIII, thus becoming part of the royal domain.

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In 1226, Louis IX, the future Saint Louis, took up residence at the château and had the Royaumont Abbey built. During the 14th and 15th centuries, the château underwent numerous assaults, destructions and reconstructions: the Hundred Years' War, sieges by the English, French, Burgundians and Armagnacs. The castle and town were occupied by the English between 1420 and 1435. The last major transformation of the château took place in the 18th century.

With the advent of artillery, weapons became increasingly powerful, and the castle's defensive structure had to be reinforced. The height of the keep was reduced from 37 meters to around 5 meters. The castle became an artillery stronghold. The château then lost its grandeur and was abandoned in 1815.

Heritage Days 2026: Exploring the region’s most beautiful castles in Paris and Île-de-France
Heritage Days 2026 also offers the chance to visit the castles of Île-de-France, often for free! Kings and queens, princes, emperors, nobles of every kind... Step in the footsteps of these towering figures in French history and discover their magnificent residences, on 19 and 20 September 2026. [Read more]

The 2026 Heritage Days program at the Château de Beaumont-sur-Oise (95)

Men, women and children who resisted in Beaumont-sur-Oise
A route marked by the names of 18 people, spread across ten commemorative stops that mark the places where these resistance fighters operated throughout the city.
Participation conditions: Free | No reservation required
Schedule: Saturday, September 19, 2026 — 10:30 AM to 12:00 PM
Beaumont-sur-Oise Castle
Visit to Beaumont-sur-Oise Castle, tracing its story from Gallo-Roman roots through the archaeological digs of the 1980s and 1990s, and crossing the medieval era marked by the prominence of theCounts of Beaumont and the residence of the kings of France, up to the modern period when the fortress served as a strategic artillery site defending Paris.
Participation conditions : Free admission, tours depart roughly every 30 minutes — Free | No booking required
Hours: Saturday, September 19, 2026 — 3:00 PM to 5:00 PM | Sunday, September 20, 2026 — 10:00 AM to 12:00 PM, 2:00 PM to 6:00 PM