Salzburg is the main hub for visiting the Eastern Alps, with frequent rail service from Vienna. Bad Gastein is also connected to Vienna, but with fewer direct trains; to get to Zell am See you must change trains in Salzburg. Most of the towns in the Eastern Alps are reachable by train, but the Grossglockner is reachable in a practical sense only by road.
If your onward travel plans from the Eastern Alps point you in the direction of Vienna, or you plan to travel to Carinthia after flying into Vienna, keep in mind the route via the Semmering Railway. It is now a section of rail travel that is part of the Austrian network, but the 41 km (25 miles) that is still called the Semmering is probably the most spectacular regular guage train journey you will ever take. And it has been in constant use for 160 years. Built between 1848 and 1854, it traverses high mountain terrain between Gloggnitz, southwest of Vienna, to Murzzuschlag over the Semmering Pass. It's commonly referred to as the world's first true mountain railway and a marvel of civil engineering. It features 14 tunnels, 16 viaducts (some of them two stories), more than 100 curved stone bridges and 11 small iron ones. It's possible to incorporate traveling this wonder on your way to or from Vienna and Klagenfurt, Heiligenblut or Zell am See. Get information about tickets and timetable from ÖBB (Austrian Railways).
Österreichisches Bundesbahn. 05/1717; www.oebb.at.