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
Of the half dozen trade posts in Sweden described in 1120 as cathedral cities, or cities with a potential to become such, Sigtuna is believed to be the only one with the density and status of a city in the proper sense. This quickly changed as German merchants introduced developed forms of production and 'industrialised' Swedish mining, mostly during the second half of the 13th century. This rewrote the regional map and resulted in the gradual development of a Swedish urbanity. As trade routes moved westward in the Mälaren region, Sigtuna found itself left astern.
Birger jarl's elimination of the "true Folkungs" between 1247 (Battle of Sparrsätra) and 1251 (Battle of Herrevadsbro) lead to increased consolidation of the Swedish kingdom and the introduction of a continental feudal society. Additionally, the Swedish dominion expanded east as Birger jarl and Torgils Knutsson conquered Tavastland and Karelia (later Finland) which placed present-day Stockholm, until then an insignificant peripheral island, in the absolute centre of the small empire.