Brennender Berg

On the border between Saarbrücken and Sulzbach/Saar, an underground coal seam has been smoldering since the 17th century — visible as wisps of smoke rising from the ground, warm soil underfoot, and a patchwork of heat-tolerant vegetation unlike anything in the surrounding forest. The fire is thought to have ignited through an uncontrolled mine burn in the early 1600s; despite occasional attempts to extinguish it, it has never fully gone out. Protected today as a natural monument, the Brennender Berg is one of Germany's rare places where deep geological forces make themselves directly perceptible at the surface. Short hiking trails cross the site, and at several points the warmth of the ground and a faint sulfurous smell make the subterranean blaze unmistakably real.