For a long time during the Middle Ages, Goslar was an imperial palatinate where the Holy Roman Emperors held their court councils. The old town center has been a UNESCO World Heritage site since 1992. Two thirds of its buildings are historically listed. Their elaborate ornamentation testifies to the status and wealth of their former owners. The Old Town still has about 1500 half-timbered buildings crowded into an area a mere square kilometer in size. The town owes its rise and wealth to a rich vein of metallic ore discovered on Rammelsberg mountain, about two kilometers away. The mine was decommissioned in 1988. Now it's a museum and also a World Heritage site. In the permanent exhibition there's a sculpture by the American artist John Chamberlain. It depicts a horse whose hooves, legend has it, laid bare the mountain's vein of ore when he pawed the ground waiting for his master, a knight called Ramm. The mountain was named Rammelsberg in the knight's honor. Goslar also has a soft spot for modern art. The Mönchehaus Museum houses works by Georg Baselitz, Joseph Beuys and Max Ernst. It also displays works by the winners of Goslar's Kaiser Ring Award, presented annually to deserving artists.