Erasmus Lueger was a 15th century knight born into privilege: his father, Nikolai Lueger, was imperial governor of Trieste. He was a close friend of the mercenary commander Andreas Baumkircher, and when Marshal Pappenheim, commander of the imperial army, insulted Baumkircher after his death, Erasmus killed him. That act made him a target of Holy Roman Emperor Frederick III, and he fled to his family’s stronghold, Predjama Castle near Postojna in Inner Carniola, in modern Slovenia. First built in 1274 in Gothic style by the patriarch of Aquileia, the castle sits high in a limestone cliff inside the mouth of a cave, so the mountain forms its back and sides.

From there Erasmus allied with King Matthias Corvinus and raided Habsburg estates across Carniola, until the emperor sent Andrej Ravbar, the new governor of Trieste, to besiege him. Erasmus used a widened natural shaft in the karst rock, which opened on the clifftop about 25 meters back from the edge, to bring in supplies and keep raiding, reportedly tossing fresh food down to taunt the besiegers. He was eventually killed, and a legend spread that a servant signaled with a candle while he sat on the lavatory. The castle was rebuilt, wrecked by an earthquake in 1511, and rebuilt in Renaissance form by 1570 under Baron Philipp von Cobenzl.

• Why medieval honor codes made violent retaliation a matter of survival
• How the cave site forced attackers into a single steep frontal approach
• Why the Habsburgs benefited from a humiliating story about his death
• Later owners including the Cobenzl, Coronini von Cronberg, and Windischgrätz families
• Nationalization by Yugoslav communist authorities after World War II and its new life as a museum