The ancestor of all mountain rail lines is celebrating its 150th anniversary: The Semmering line - a section of the railroad connection between Vienna and Trieste - was the first rail line built through the high mountains. Its construction from 1848-1854 was absolutely new territory. During the six years of planning, various alternatives were rejected such as going around the Alps, support with horses or cable cars. The decision was made for a double track line with pure adhesion operation with steam locomotives. This was a visionary concept for the technology of that time and was the prototype for all subsequent alpine crossings. Almost 42 km or 26 miles of line were required for the 21 km or 13 miles as the crow flies between Gloggenitz and Mürzzuschlag in order to allow steam locomotive operation on the grades. Fifteen tunnels and 16 viaducts (climbing and curved viaducts for the first time) were built. The Semmering line has been electrified since 1959 and is still a much traveled line down in north-south traffic. The Semmering line was declared a world cultural heritage by UNESCO in 1998 due to its prototype function, the standardized classicistic architectural style and the thoroughly original preserved viaducts, station buildings, and tunnel portals.