A crane, a method for assembly of a crane and a method for disassembly of a crane are disclosed. In accordance with the method, a first mast is fixed in a vertical position. A top mast section of a second mast is positioned adjacent to and outside of the first mast. The top mast section is moved vertically upwards, and this movement is guided by a guide system. Then, the top mast section is fixed relative to the first mast at a position which is at a larger vertical distance from the crane base. Then, a first intermediate mast section of the second mast is fixed to a lower end of the top mast section to build up the second mast. Then, the first intermediate mast section is connected to a pivot, and the second mast is pivoted away from the first mast.