Lhotse (E1) consists of three Himalayan summits on the Nepalese-Tibetan (Chinese) border just south of Mount Everest, to which it is joined by a 25,000-foot (7,600-metre) ridge. On May 18, 1956, Fritz Luchsinger and Ernest Reiss, two Swiss climbers, made the first ascent of the mountain. It is sometimes considered part of the Mount Everest massif. Lhotse is Tibetan for “south peak”; E1 was the original survey symbol (denoting Everest 1) given by the Survey of India (1931).