Église de l'Annonciation de Haute-Isle, Troglodyte church in Haute-Isle, France

The Annunciation Church is a place of worship built partly into the chalk cliff along the Seine River, with a stone bell tower rising above ground. The main worship space tunnels into the rock face, creating an unusual setting where the building merges with the natural landscape.

The church was cut into the chalk cliff in 1670/1673 at the expense of Nicolas Dongois, lord of the place, after the village was erected as a parish. It was listed as a monument historique on 4 June 1926. Closed in 1999 over collapse risk, it has since reopened and serves the pastoral sector of Magny-en-Vexin.

The choir is closed by a carved and gilded wooden screen, thought to come from the chapel of the Rouen courthouse. The wooden altarpiece dates from the church's origins and was modified in the 18th century; both are listed as historical objects.

The church stands on the route de la Vallée (RD 913), with a terraced cemetery at the foot of the chalk cliff leading to it. There is no tower entrance: the doorway opens directly into the excavated nave. The building was closed in 1999 over collapse risk, then reopened and now regularly hosts services of the Magny-en-Vexin pastoral sector.

The church owes its protected status less to archaeology than to rarity: it was listed in 1926 for the unusual character of the site. Since the destruction of the church at Mousseaux-sur-Seine in 1749, it has remained the only rock-cut church in Île-de-France.