Crane assemblies and methods for erecting towers and wind turbines

A crane assembly for erecting a tower from a plurality of tower sections, the crane assembly comprising:

• a first telescopic mast;
• a second telescopic mast connected to the first telescopic mast;
• a crane mounted on top of the first telescopic mast;
• the first telescopic mast configured to increase in length from a retracted state in a first direction and comprising a first clamp assembly configured to selectively grip portions of the tower;
• and
• the second telescopic mast configured to increase in length from a retracted state in a second direction opposite to the first direction and comprising a second clamp assembly configured to selectively grip portions of the tower.