Exclusive to: Hamlet.
Watch Towers are a structure exclusive to the Hamlet DLC that can be found in the Pig City and Pig City Outskirts biome. When damaged with a Hammer and reduced to rubble, a Royal Guard will spawn to protect the tower. Watch towers will be repaired by Worker pigs if they have been damaged. Watch Towers can be built by the player if they are holding a Key to the City. They cannot be set on fire. Royal Guard respawns after 3 days if killed.
If one wants Royal Guards around in a vanilla Don't Starve or Reign Of Giants world, at least one Halberd should be brought through the Skyworthy alongside the Key to the City. Further Halberds can be obtained by spawning and killing Royal Guards.