Alstahaug Church lies in the south of the municipality, some miles to the south of Sandnessjøen. The oldest part of the church is believed to date from the early years of the thirteenth century. The church is known for its onion-shaped dome. The church has been extended, restored and refurbished many times during its history, most recently in 1960. The church served as a cathedral from 1805 to 1928 and was the church of poet and clergyman Petter Dass.
