Mästerby Church dates largely from the 13th century. The nave, choir and apse were built first, at the beginning of the century. In the middle of the same century, the tower was also built. The nave was made higher about a century later, and at this time both the nave and choir received vaulted ceilings. The church has remained relatively unaltered since the end of the Middle Ages. Only the sacristy is significantly later, added in 1790. New windows were also made in the 1860s.
The church is richly decorated with frescos internally. They range in period from the 13th to the 17th century. In the apse, some Romanesque paintings survive, notably a depicting of Mary, while some have been covered with other paintings in the 17th century. The vaults in the nave are decorated with frescos from the 14th century, and the walls of the nave furthermore decorated by the artist sometimes referred to as the Master of the Passion of Christ (15th century). Still other frescos, in the choir, probably date from the 16th century, while another set, again in the nave, is dated to 1633.
The baptismal font is from the 12th century, Romanesque in style and a work by the sculptor known by the assigned name Byzantios. The triumphal cross is locally made, dating from the 13th century. Other furnishings date from the time after the Reformation.
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.