Chêne Chapelle
The Chêne chapelle (“chapel oak”) is an oak tree located in Allouville-Bellefosse in Seine-Maritime, France.
The oak tree is between 800 and 1,200 years old. It is 15m high and its base has a circumference of 16m. Its hollow trunk hosts two chapels, which were built there in 1669: Notre Dame de la Paix (“Our Lady of Peace”) and the Chambre de l’Ermite (“Hermit’s room”). A spiral staircase around the trunk provides access to the chapels.
The Oak Chapel still stands and can be seen in modern photographs here.
(Source: Wikipedia)