What a tunnel looks like?

A tunnel is a long, enclosed passageway that is typically dug through earth or rock, often featuring a cylindrical or arched shape. The walls are usually rough and dark, with occasional support beams or lighting fixtures to enhance visibility. Inside, it can feel cool and damp, with the sound of dripping water or echoes of footsteps. Tunnels can vary in size, from narrow pathways for pedestrians to wide passages for vehicles or trains.