Whether or not you ever raved in a quarry, here’s one you’ll be raving about. Vienna’s St. Margarethen Quarry is a UNESCO World Heritage site and one of the oldest and most impressive in Europe. On this guided tour through its sandy limestone history you'll hear what ancient fossils have been discovered, how the stone helped to build and restore Vienna, and why the huge outdoor concert hall is one of the best venues in the world to experience opera.The limestone in Vienna’s St. Margarethen Quarry has been put to pretty good use over the years. Much was used in the construction and restoration of St. Stephen’s Cathedral, and for the buildings around the Ringstrasse in Vienna. The space was molded and carved by a prehistoric inland sea, and some of the fossils dug up in this quarry are 25-million years old! That’s quite a venue already, but the acoustics and romantic atmosphere here also make it one of the best for opera. Countless famous singers have taken to the stage to sing in front of 5,000 people from one of Europe’s biggest open-air stages. Soak it all up as you stroll around the awesome space with your English-speaking guide. A tour oozing culture and history like this is hard to beat in Austria. And if you feel like coming back at sunset, watching a performance here is highly recommended too.