Riddarfjärden
Riddarfjärden (, "The Knight Firth") is the easternmost bay of Lake Mälaren in central Stockholm. Stockholm was founded in 1252 on an island in the stream where Lake Mälaren (from the west) drains into the Baltic Sea (to the east); today the island is called Stadsholmen and constitutes Stockholm's Old Town.
Prehistory and origin of Stockholm
The first town in the Lake Mälaren region was undoubtedly Birka on Björkö island about 20 km west of present-day Stockholm. Founded in the late 8th century, it was described by Rimbert, Archbishop of Hamburg-Bremen, who wrote about his predecessor Ansgar's missionary journeys c. 830 and 850. For unknown reasons, Birka was deserted around 975. Shortly thereafter, Sigtuna appeared on the northern shores of Mälaren. Located on the main navigable approach to Uppsala, Sigtuna is believed to have been designed as missionary outpost and a Christian trade centre rivalling the still pagan Uppsala. While Sigtuna saw its heyday during the 10th century, the Blackfriars decided to construct their first monastery in Sweden at Sigtuna in the 1230s (inaugurated 1247), which seem to indicate Sigtuna was still the city dominating the Mälaren region at that time.
Notwithstanding surviving records makes it difficult to see exactly when and in what order events took place, several causes for the development to occur in the 13th century can be distinguished: