(n.) A tower in which a sentinel is placed to watch for enemies, the approach of danger, or the like.

Texas tower beacon belvedere bench mark bleachers bookmark bridge cairn catstone conning tower gallery gazebo grandstand landmark lighthouse lightship lookout loophole mark marker menhir milepost milestone monument observation post observatory outlook overlook peanut gallery peephole pharos platform ringside ringside seat seamark sighthole top gallery tower