On the 28th of July, 1830, a cannon was aimed at the Hôtel de Sens in Paris. The powder exploded, and the projectile, a lump of iron weighing several kilograms, collided with the stone with a hefty thunk. Instead of breaking the stone or bouncing off harmlessly, it embedded into the side of the hotel, … More The Cannonball Lodged in the Wall of the Hotel de Sens