When people think of Bad Gastein, they often picture a picturesque alpine town in the heart of Salzburg – with a dramatic waterfall in the middle of the historic center, elegant Belle Époque buildings, and 200 kilometers of ski slopes. But Bad Gastein is much more than a paradise for nature lovers or skiers. It is also one of Austria’s most renowned spa destinations – and home to a world-unique healing experience: the Gastein Healing Radon Galleries, known as Gasteiner Heilstollen. Unlike typical wellness centers, the Heilstollen is a specialized medical facility where patients undergo a remarkable therapy several times a week. Each session – called an Einfahrt – begins with a small train ride 2.5 kilometers deep into the mountain. Inside, a unique microclimate awaits: temperatures over 40°C, 100% humidity, and naturally occurring low-dose radon in the air.