A barrel vault is an architectural structure formed by extending a simple arch along a length. This design creates a continuous, curved ceiling that resembles a barrel, hence the name. Barrel vaults are often used in large spaces like cathedrals and tunnels, providing both strength and aesthetic appeal. These vaults distribute weight evenly along their curves, allowing for the construction of wider and taller spaces without the need for numerous supporting columns. They were commonly used in ancient Roman architecture and continue to influence modern design in various buildings and structures.