This Oak Tree is located in France, in a Normandie's town called "Allouville-Bellefosse". It is one of the oldest tree in the country, with around 1200 years. 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.
As for the photo itself, I wanted to show that it actually is in a city, hence this angle showing the right wall and houses. About the distortion, the shot was made with a tilt-shift lens, which is supposedly used to *correct* parallelism problems... but I actually had fun using it the other way: I liked the special atmosphere it gave to the location. It is quite a fun piece of gear!