Nyköping Municipality is a municipality in Södermanland County in southeast Sweden. Its seat is located in the city of Nyköping. Its southern tip in the district of Tunaberg is the southernmost point of mainland Svealand, one of the three original crowns forming Sweden.
The municipality was created in 1971 with the amalgamation of the City of Nyköping and a great number of other municipalities. It was split up in three parts in 1992, when Gnesta Municipality and Trosa Municipality were created.
Wikipedia https://en.wikipedia.org/wiki/Nyköping_Municipality
Coordinates 58°46'4.914" N 17°3'56.457" E
