The Xel'Naga Tower (Also known as the Xel'Naga Watch Tower, Watch Tower or Observatory) is an indestructible neutral structure that reveals an area of radius 22 around it when activated by a unit.
Xel'Naga Towers are usually placed in strategic locations of the map to provide advantages for the controlling player. They can cover base entrances (as in Shattered Temple), areas with high traffic ( as in Scrap Station and Xel'Naga Caverns), and important expansions (as in Backwater Gulch).
Xel'Naga towers provide a large area of vision to a controlling player, who can receive information about their opponent while preventing their opponent from receiving the tower's information. Players frequently contest Xel'Naga towers to gain map control, as the tower's information can enable the controlling player to make better decisions and react more quickly to their opponent.
- The Xel'Naga Tower will activate and remain activated while a unit remains within a 2.5 range.
- The Xel'Naga Tower will deactivate when two enemy units are within its activation range.
- The Xel'Naga Tower does not detect cloaked units.
- A Siege Tank in Siege Mode can activate the Xel'Naga Tower.
- Cloaked units can activate the Xel'Naga Tower.
- Summoned units such as Changelings and Infested Terrans can activate the Xel'Naga Tower.
- Burrowed and Flying Units cannot activate the Xel'Naga Tower.
- Buildings cannot activate the Xel'Naga Tower. This includes Auto-Turrets, Spine Crawlers and Spore Crawlers (regardless if they are deployed or walking), and Bunkers (even if units are inside).
- An idle worker within range of a Xel'Naga Tower will not be reported as an idle worker by the UI, and will not be selected by pressing Ctrl-F1.