Tour de Sauvabelin is a wooden observation tower in the Sauvabelin Forest above Lausanne. It was designed by Julius Natterer from the IBOIS lab at EPFL.
Built in 2003, 151 steps lead up to the observation platform at an altitude of 700m above sea level or 328m above the shore of Lake Geneva. It has a total weight of 130 tons and uses Douglas fir, spruce and larch from Lausanne's forests.
The stairs are built using beams that are fixed on a central axis thus creating a double helix and separating the staircase leading up from the one descending.