Heritage Days 2025 at the Annonciation troglodyte church (95), the program

On September 20 and 21, 2025, the Journées Européennes du Patrimoine (European Heritage Days) will be opening the doors to the unsuspected treasures of Paris and the Île-de-France region. In Val-d'Oise (95), head for Haute-Isle for a mineral immersion in the region's only troglodyte church, carved right into the cliff.

The European Heritage Days return on September 20 and 21, 2025 with a promise: to make the heart of history beat to the rhythm of discovery. Île-de-France is transformed into a cultural playground, where curiosity and wonder become your best guides. Two days of wide-open doors to touch - sometimes literally - the soul of the most emblematic, most unusual and sometimes most secret places. Castles, museums, gardens, curiosities... Heritage can be experienced, listened to, smelled and enjoyed in a whole new way. It's the perfect opportunity to explore History with a capital H, in a sensory version that's freely accessible!

Did you know? There's an unusual troglodyte church in the Val d'Oise, just waiting to be discovered.
Did you know that in the Val d'Oise, the Church of the Annunciation at Haute-Isle is the only troglodyte church in the entire region? Carved directly into a chalk cliff and listed as a historic monument, it's an unusual nugget to discover. [Read more]

Why not dig a little deeper? Let's head for the Val-d'Oise (95), more precisely Haute-Isle, for a divine visit in both the literal and figurative sense: that of thetroglodyte church of the Annunciation. Carved out of the chalk rock between 1670 and 1673 at the request of Nicolas Dongois, the King's secretary, this church, the only one of its kind in Île-de-France, is the envy of the finest architectural gems. Entirely excavated from the cliff, only its masonry bell tower proudly protrudes from the hillside. At 26 metres long, 8 metres wide and 8 metres high, the nave is austerely mineral. Listed on the Inventaire Supplémentaire des Monuments Historiques since 1926, it continues to host services and ceremonies. As an added bonus, it's just a stone's throw from the troglodyte château of La Roche-Guyon!