The Semmering railway, which starts at Gloggnitz and leads over the Semmering to Mürzzuschlag was the first mountain railway in Europe built with a standard gauge track. It is commonly referred to as the world's first true mountain railway, given the very difficult terrain and the considerable altitude difference that was mastered during its construction. It is still fully functional as a part of the Southern Railway which is operated by the Austrian Federal Railways.
The Semmering railway was constructed between 1848 and 1854 by some 20,000 workers under the project's designer and director Carl von Ghega born in Venice as Carlo Ghega in an Albanian family. The construction features 14 tunnels (among them the 1,431 m vertex tunnel), 16 viaducts (several two-story) and over 100 curved stone bridges as well as 11 small iron bridges. The stations and the buildings for the supervisors were often built directly from the waste material produced in the course of tunnel construction.
In 1998 the Semmering railway was added to the list of the UNESCO World Heritage sites.
References:Celje Castle was once the largest fortification on Slovenian territory. The first fortified building on the site (a Romanesque palace) was built in the first half of the 13th century by the Counts of Heunburg from Carinthia on the stony outcrop on the western side of the ridge where the castle stands. It had five sides, or four plus the southern side, which was a natural defence. The first written records of the castle date back to between 1125 and 1137; it was probably built by Count Gunter. In the western section of the castle, there was a building with several floors. Remains of the walls of this palatium have survived. In the eastern section, there was an enclosed courtyard with large water reservoirs. The eastern wall, which protects the castle from its most exposed side, was around three metres thicker than the rest of the curtain wall. The wall was topped with a parapet and protected walkway.