watchtower

noun watchtower

• lookout — Cape, a sandy reef in the Outer Banks, off E North Carolina, SW of Cape Hatteras: lighthouse.
• barbican — a walled outwork or tower to protect a gate or drawbridge of a fortification
• beacon — A beacon is a light or a fire, usually on a hill or tower, which acts as a signal or a warning.
• landmark — a prominent or conspicuous object on land that serves as a guide, especially to ships at sea or to travelers on a road; a distinguishing landscape feature marking a site or location: The post office served as a landmark for locating the street to turn down.
• lighthouse — a tower or other structure displaying or flashing a very bright light for the guidance of ships in avoiding dangerous areas, in following certain routes, etc.