Sigtuna Municipality is a municipality in Stockholm County in east central Sweden. Its seat is located in the town of Märsta, approximately 37 km (23 mi) north of the Swedish capital, Stockholm.

Märsta is a suburb of Metropolitan Stockholm, a locality and the seat of Sigtuna Municipality, Stockholm County, Sweden with 27,034 inhabitants in 2015. The town is situated close to Stockholm's main international airport, Arlanda. Even though its origins go back to around 500 AD, Märsta is a widespread modern residential area. Märsta has a mix of multi-storey dwellings and smaller houses. It is in a phase of expansion and new residential areas are built both in central parts of Märsta and in the surrounding areas like for instance Steningehöjden. Märsta can be reached by Stockholm commuter rail trains running at quarterly intervals during daytime and by bus from Stockholm Arlanda Airport. The central parts of Märsta has a shopping area "Märsta Centrum" with various shops, pub and restaurants. Another smaller shopping area is "Valsta Centrum". East of the central parts of Märsta there is an industrial area and a bit further east close to the airport a shopping mall "Eurostop". Most parts of Märsta and the municipality of Sigtuna can be reached with local bus services originating at the Märsta Railway Station and also connecting with commuter trains.