Central Stockholm has four different parts - Kungsholmen, Södermalm, Norrmalm and Östermalm. Kungsholmen and Södermalm are islands, while Norrmalm and Östermalm are parts of the mainland. Also, there are several smaller islands in the inner city - Gamla Stan, Riddarholmen, Djurgården and Skeppsholmen. Since Stockholm has so many islands, it is sometimes referred to as the "Venice of the North".