St. John's Church was built between the 12th and 16th centuries, though there must have been churches preceding it. It was heavily damaged during World War II, but it has been restored. The oldest part of the building is the Romanesque tower. The tower dates from the early 13th century.
The choir, in part likewise from the 13th century, is a mixture of Romanesque and Gothic elements, and features two side chapels. To the left of the choir is the vestry, above which there is a room that must once have served as a chapel.
The 14th-century nave is now quite low, as it is covered by a modern ceiling inspired by that of the vestry.
The chapel to the south of the nave dates from the 15th and 16th centuries. Its two bays have Gothic vaults. The vaults of the northern aisle, which an inscription dates 1513, are flamboyant Gothic.
References:The church of the former Franciscan monastery was built probably between 1515 and 1520. It is located in the UNESCO World Heritage Site of Old Rauma. The church stands by the small stream of Raumanjoki (Rauma river).
The exact age of the Church of the Holy Cross is unknown, but it was built to serve as the monastery church of the Rauma Franciscan Friary. The monastery had been established in the early 15th century and a wooden church was built on this location around the year 1420.
The Church of the Holy Cross served the monastery until 1538, when it was abandoned for a hundred years as the Franciscan friary was disbanded in the Swedish Reformation. The church was re-established as a Lutheran church in 1640, when the nearby Church of the Holy Trinity was destroyed by fire.
The choir of the two-aisle grey granite church features medieval murals and frescoes. The white steeple of the church was built in 1816 and has served as a landmark for seafarers.