Semmering, Or Sommering, a branch of the Noric chain of Alps, between Austria proper and Styria, 4,416 ft. high, containing the principal pass between Lower Austria and the more southern provinces of the Austrian empire. In the 14th century a duke of Styria founded a hospital for travellers on the Styrian side of the pass. A post and carriage road over the mountain was completed by the emperor Charles VI. in 1728; it rises, partly by zigzags, upward of 3,000 ft. above the sea. A new highway, longer, but more practicable, was completed in 1840. A railway over the Semmering, projected and undertaken by a private company, was executed for the Austrian government by the engineer Carlo Chega between 1848 and 1854. It extends 25 m. from Gloggnitz, at the N. extremity of the pass, to Mürzzuschlag, at the S. extremity. It rises from Gloggnitz, crossing the Schwarzer on a curved viaduct of 13 arches, and sweeping along the shoulders of the hills through a series of magnificent engineering works, including 15 tunnels and 15 bridges, till it attains a height of 2,893 ft. above the sea, when any further ascent is avoided by a tunnel nearly a mile long.