Sigtuna is one of the oldest towns in Sweden. It was founded about 970. The town was probably built to concentrate royal power to the Mälaren Valley. We know that it was a royal town, because Sweden’s oldest workshop for making coins has been found in Sigtuna. It was used between 990 and 1035. In the 1070s, Sigtuna is also mentioned as an archdiocese.
Two of the numerous rune stones in Sigtuna mention that Frisian guilds were in the town, that is associations of merchants from present-day Netherlands and Belgium. It indicates trading contacts with the North Sea coast as early as in the 11th century. Probably, farm produce from the province of Uppland was sold to the Frisians, who might have brought cloth and salt in return.
Sigtuna lost its role as Sweden ´s religious centre when the Archbishop moved to Uppsala in 1164. Around 1250, however, a Dominican friary was built in the town. The church of the friary, Mariakyrkan, is still there as well as part of its medieval fittings.
The King’s and the public officials’ offices were moved to Stockholm when the town was founded in the 13th century.