In 1893, Adolf Guyer-Zeller conceived of the idea of a railway tunnel to the Jungfraujoch to make the glaciated areas on its south side more accessible. The building of the tunnel took 16 years and the summit station was not opened before 1912. The goal was in fact to reach the summit of the Jungfrau with an elevator from the highest railway station, located inside the mountain. The complete project was not realized because of the outbreak of the World War I.