Semmering Pass, Mountain pass in Eastern Northern Limestone Alps, Austria

Semmering Pass is a mountain crossing at 984 meters elevation in the Eastern Northern Limestone Alps. The route links Lower Austria and Styria, creating a natural transport connection between these two Alpine regions.

One of the world's oldest mountain railways was constructed here in 1854 using innovative engineering to overcome steep slopes. This railway line received UNESCO World Heritage status in 1998 for its historical significance.

The name Semmering probably comes from the Slavic "Semernic", recorded in 1227 and often explained as "the inhospitable one", though "Smrk" (spruce) and "Cemerinik" (mountain by the hellebore) are also proposed. German settlers kept the Slavic name and long used "Cerewald" (Swiss pine forest); the minstrel Ulrich von Liechtenstein described crossing the "Semernic" in his Arthurian travel account.

You can drive through the pass via Autobahn or local roads, both of which are regularly maintained for safe travel. Train service between Vienna and Graz across this route offers a comfortable alternative to driving.

The Semmering Railway, built 1848–1854 under Carl Ritter von Ghega, crosses the pass with 16 large viaducts, 14 tunnels totalling 1,477 m, over 118 stone arch bridges and 11 small iron bridges to overcome a 459 m height difference. It was the world's first mountain railway and is a UNESCO World Heritage Site.