Watchtower 13 was one of a series of Watchtower outposts located along the Federation side of the Romulan Neutral Zone. The outpost was constructed on an asteroid.
In 2257, Watchtower 13 was under construction. After the destruction of the USS Farragut's secondary hull, T'Cel took Lieutenant James T. Kirk to the outpost in an escape pod and left him there in a stasis tube to keep him safe from the Romulans. Construction of the outpost was abandoned shortly afterwards.
In 2286, the USS Enterprise-A under Captain Kirk, the IKS Revenge under Commander Kor and the ChR Phoenix under Commander T'Cel rendezvoused at Watchtower 13 to deal with the extra-dimensional "Critters." (TOS comic: "Debt of Honor")