Nyköping Municipality (Swedish: Nyköpings kommun) is a municipality in Södermanland County in southeast Sweden. Its seat is located in the city of Nyköping, which is containing a majority of the residents. Its southern tip in the district of Tunaberg is the southernmost point of mainland Svealand, one of the three original crowns forming Sweden. Nyköping is the administrative capital of Södermanland and hosts both the governors' residence and the regional council. The municipality was created in 1971 with the amalgamation of the City of Nyköping and a great number of other municipalities.
https://en.wikipedia.org/wiki/Nyk%C3%B6ping_Municipality