The oldest parts of the Porvoo Cathedral date from the end of the 13th century. The church was dedicated to St. Mary, and the current Gothic-style appearance is mainly from the reconstruction in 1414-1418. The building has been destroyed several times. The interior is decorated with wall paintings from the end of the 15th century, and the pulpit was made in 1764. The church became a Cathedral in 1723, and has a seating capacity of 750. The belfry's oldest parts date from medieval times, and the present appearance is from the 18th century. The roof of the church was completely destroyed by fire in May of 2006.

The small church was dedicated in 1740. It has been used by the Porvoo Lutheran parish of Finnish speaking people. The church was restored in 1973-1974. It has two altarpieces of which one dates from 1892, and the other was painted in 1833. The pulpit is from the 19th century, and the organ dates from 1887. The small church is located next to the belfry of Porvoo Cathedral.