The medieval St. Mary's Church in Hamina is the oldest building in Kymenlaakso and a fascinating destination for those interested in history and architecture. The 550-seat stone church dedicated to the Virgin Mary was probably built on its present site before 1396. The medieval paintings on the eastern wall of the church still remain.

The church has experienced many destructions and repairs, such as the Great Fire of Hamina in 1821, after which the church itself was repaired under the direction of C.L. Engel, who also built the present bell tower.

The church's surroundings and the floor beneath it are the resting places of many old inhabitants of the village. A memorial plaque in the armoury and a monument designed by Esko Ahlberg commemorate this. On the wall of the church tower is an engraving made in 1964 by Sulo Mäkelä, an artist from Vehkalahti.

St. Mary's Church also offers an opportunity to explore the artefacts from the 1700s on display in the museum room in the south wing of the church. The altarpiece of the church, which depicts the Last Supper