Gaustatoppen is a mountain in Telemark county, Norway. The 1,883-metre tall mountain is located on the south side of the town of Rjukan. It is the tallest mountain in all of Telemark county. The peak of the mountain lies in Tinn Municipality, but there is a lower plateau that crosses over the municipal border into Hjartdal Municipality. The view from the summit is impressive, as one can see an area of approximately 60,000 square kilometres, nearly one-sixth of Norway's mainland.