Temppeliaukio Lutheran Church is one of the biggest attractions in Helsinki. It was designed by the Suomalainen brothers, both architects. It was officially opened in 1969. The interior was excavated out of rock, but is bathed in natural light through its glass dome. The church is often used as a concert venue due to its excellent acoustics. This quality is achieved by rough rock surfaces that give the impression of a cave more than a church. The furniture of the church was also designed by the architects.