Kungsholmen is in Stockholm. Kungsholmen is a district as well as an island. The district of kungsholmen consists of three islands. Lilla Essingen, Stora Essingen and the Kungsholmen island.
There are several subway stations in Kungsholmen. On the green line you have Fridhemsplan, Thorildsplan and Kristineberg and on the blue line you have Fridhemsplan, Rådhuset and Stadshagen.
The City Hall  or Stadshuset as it is called in Swedish is a fascinating building and one of the landmarks of Stockholm. Here the Nobel Prize Banquet takes place on the 10th of December every year.