Deployable lookout tower

A Deployable Lookout Tower is an anti-gravity-operated tower in use by the Covenant. They are mainly used to fortify specific areas on a battlefield.

Summary
A Deployable Lookout Tower is comprised of a circular base, in the middle of whom an anti-gravity generator is placed. An also circular platform is suspended in the air, given the anti-gravity power by the generator. The platform has also a gap in the middle for the ferries to be transported. The anti-gravity generator works just like a gravity lift, transporting supplies and troops freely. It also has the same color as the gravity lift.

The perimeter of the base is comprised of three ramps, and three pillars, probably put there for extra protection. They are all placed in a motive (one ramp-one pillar). The platform has also three protective pillars and large gaps between them. The pillars are taller and thinner compared to the ones of the base. Also, the gap between them is bigger. The gap is used for snipers to have a clear line of sight and for gunners to place their Plasma Cannons. Some Towers' platforms, instead of the usual oval pillars, have three thinner, longer pillars that support a rooftop-like cover.

The base, when placed on the ground, can't be moved again. The platform, however, is not as steady as the base. A single shot from the Rocket Launcher or the Fuel Rod Gun from distance and the Shotgun from nearby will make it lose it's balance and it may fall off. Three shots from the Rocket Launcher are sure to make it fall.

The tower is able to garrison a whole File, but usually single Jackal Snipers, Brutes with Carbines and Heavy Grunts will occupy it.

In-Game Appearances
In Halo 2, the platforms are destructible. The player can climb on them by the anti-gravity lift, and he can use it just like any Covenant. However, his position becomes highly exposed then. They appear in numerous Campaign maps as well as in the multiplayer map, Relic.

In Halo 3, they are destructible again. They are also able to be climbed. They appear in some Campaign levels as well as many multiplayer levels.

In Halo Wars, they are deployed by the Covenant, but once every single Covenant troop on it is destroyed, UNSC soldiers can garrison in it, increasing their combat capabilities. A Covenant File is usually found on top of them defending the Jackals and Heavies there. In multiplayer, they are left neutral for either team's taking, providing a useful defense, if needed.

Glitch
On all Halo 2 gravity towers that have been knocked down, the base is still active and can be used to push you up directly into the air. From this position, you can continue to hover and snipe enemies. This glitch is absent from Halo 3; once the tower is destroyed, the gravity lift of the base does not work. However, the tower itself (if still intact) will push you through the hole in the center, as if the gravity lift was under it.

Trivia

 * Halo 2 is the only game in the trilogy to use Deployable Lookout Towers in multiplayer. Halo 3 may contain Deployable Lookout Towers in multiplayer in future map pack releases or as Forge items, but this is unlikely.
 * If the top part of the tower is flipped upside down while a Grunt is on the Plasma Turret, the Grunt will keep firing normally.
 * In Halo Wars the tower is invincible and even a Scorpion cannont destroy it where in Halo 3 the tank will destroy one on Legendary with ease.