Mülenen, Bern (Switzerland) - "Niesen-Treppenlauf". The world's longest staircase is located on Mt. Niesen in Switzerland, nicknamed the "Swiss Pyramid" for its triangular shape. The 3.4 km staircase goes up the side of the mountain with 11,674 steps, ranging from an altitude of 700 meters at the bottom to 2363 meters at the summit of the mountain. www.niesen.ch/treppenlauf