The Temppeliaukio church is one of the most popular tourist attractions in Helsinki city. The interior of the church was excavated and built directly into the rock, but is bathed in natural light entering through the glass dome. The church is used frequently as a concert venue due to its excellent acoustics. The acoustic quality is ensured by the rough, virtually unworked, rock surfaces. The back wall of the altar is a majestic rock wall, originally created by a withdrawing glacier.