Sigtuna is a city in central Sweden in the metropolitan area of Stockholm. It has a population of 7,000 and is the namsesake of Sigtuna Municipality, even though the seat, Märsta, has 23,000 inhabitants.
Although less significant today, Sigtuna has an important place in Sweden's early history. The history of Sigtuna before the 11th century, as described in the Norse sagas and other early medieval sources, can be found in the article Old Sigtuna.
Sigtuna was founded on what was then the shore of lake Mälaren about 1,000 years ago. It took its name from an ancient royal estate several kilometers to the west. Various sources claim King Eric the Victorious as founder while others claim King Olof Skötkonung.