Originally there was a chapel situated on the site of the current Aa-kerk church. This chapel was devoted to Mary and to Saint Nicholas, the patron of the bargees who cast off the vessels at the Westerhaven.
In 1247, the chapel became the parish church and was named Onze Lieve Vrouwe ter Aa (Our Lady at the Aa) - Aa being the nearby river. Groningen had two centers at the time. One of them was around the chapel. Here lived the fishermen and the traders. Between 1425 and 1465, the chapel was changed into a brick church with a transept.
Images of the Siege of Groningen in 1672 show Der Aa-kerk without the top of the tower. After the war a new wooden tower top was built. On 23 April 1710, the tower spontaneously collapsed killing two people. In 1711, a new tower was built.
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.