Section drawing of Jungfraujoch and the Sphinx Observatory (upper right) in the Swiss Alps - railroad, elevator/lift, and other tunnels are inside the mountain - buildings (red) are exposed. Links in comments.[800x549] :
15 Berghaus Jungfraujoch Photos and Premium High Res Pictures - Getty Images
Jungfraujoch – Top of Europe | jungfrau.ch
AK Jungfraujoch, Berghaus, Observatorium | Kaufen auf Ricardo