https://i.redd.it/ixlssh7m4bhd1.jpeg

An entrance to a cave, constructed by bandits (or whoever) who actually know what they're doing. Barricades are designed to funnel attackers while giving unreachable access points for archers/casters to move around. Rubble in the cave entrance is to slow down anyone who gets past the barricades. There's even a watchtower in the corner.