In Germany’s Eifel region, viewing the power of volcanic forces is as simple as making a visit to the placid city of Mendig. Beneath the surface lies a network of basalt caves carved by human hand from ancient lava flows. The Mendig Lava Caverns make up the largest basalt mine of its kind in the world.

Residents and businesses in parts of Kaiserslautern are being evacuated after a 550-pound World War II bomb was discovered in the former Pfaff factory district, city officials said Thursday afternoon.