Peter Zumthor’s Bruder Klaus Field Chapel is located in Mechernich, Germany. The chapel is a beautiful building all the way from the interior to the exterior. The Bruder Klaus Field Chapel is in honor of patron saint Bruder Klaus of the 15th century, and was built by local farmers. The building is made with a wigwam of 112 tree trunks, then had concrete over the trunks that was about 50 cm thick. Then with a wood frame on the outside, it was set on fire to create black charred walls all the way up to the opening  to the sky in the interior of the building.

http://www.archdaily.com/106352/bruder-klaus-field-chapel-peter-zumthor