St. Mary's Church (Mariakyrkan) is the oldest still used building in Sigtuna. The brick-made church was constructed in the mid-13th century and inaugurated in 1247. It was, however, completed probably in 1255, when the archbishop Jarler was buried there. The church was enlarged and sacristy added in the 1280’s. Due the Reformation King Gustav Vasa ordered to demolish the adjacent abbey in 1530 and St. Mary's became a parish church.
The full restoration was made in the 1640’s and the present was added then. Mural paintings were restored between 1904-1905. There are couple medieval artifacts remaining in the church, like fonts, a triumph crucifix and small altarpiece.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.