Protestant worship puts the sermon at the center where the Mass puts the Eucharist, and the architecture follows: a pulpit rather than an altar as the room's focal point. Preaching is typically expository and can run forty minutes or more in traditions that take it most seriously. Congregational singing is the other Reformation innovation — the congregation sings rather than listening to a choir, which was Luther's deliberate choice and remains one of Protestantism's most distinctive sounds.