Grasdalen is a village in Tinn Municipality, in Telemark, Norway. Grasdalen lies at 286 m above sea level, in the Blefjell mountains. The nearest city is Kongsberg, 48 km to the east. Among the landmarks around are Vemork (24 km), Rjukan Line (11.6 km) and Rollag Stave Church (23 km). Among the natural features are Rjukan Falls (25 km) and Bletoppen (16.9 km).