Roman city wall in Barcelona

Rough, rectangular blocks of stone jut out from the side of the Cathedral of Barcelona, forming a stubborn, uneven stretch of masonry that predates the gothic towers surrounding it. This is a surviving section of the Roman wall built around the city of Barcino in the fourth century. When workers tried to demolish it in the nineteen fifties, they discovered that the medieval chapel tucked against it rested directly on the old Roman gate, revealing the city's ancient entrance to the modern world.