Strängnäs is a Municipality in Södermanland County, in central Sweden, located by Lake Mälaren. The municipality covers an area of 735.9 km². Total population of 30212. The population density of the community is 40 inhabitants per km². Strängnäs Cathedral, built around 1250, is an important landmark.
Many of the inhabitants of Strängnäs commute to Stockholm and Eskilstuna.