Communication Hub

The "Communication Hub" was an ancient place that was once used by the Crystal Gems thousands of years ago to communicate through space. It was located somewhere in the middle of a desert. The place made its first appearance in the episode "Coach Steven", when Sugilite demolished it with her flail.

The Crystal Gems visited it again in "Cry for Help" after discovering a transmission from Peridot, seeing that she had managed to partially repair it and use it for transmitting messages to Homeworld for Yellow Diamond to receive.

History
Not much is known about this place, considering its very brief appearance and history lecture in the episode "Coach Steven". The Communication Hub used to be a place where, at one time, Crystal Gems were able to send messages over long distances. The place contained many huge pillars adorned with triangular patterns.

In "Coach Steven", the Communication Hub had started to emit bursts of electromagnetic radiation, which, stated by Garnet, were hurting television. The Crystal Gems traveled to the hub and destroyed the structure by having Garnet and Amethyst fuse into the gigantic fusion Gem known as Sugilite who proceeded to reduce the place to rubble. Doing so, a chunk of one of the pillars destroyed the Warp Pad located by the site.

In "Cry for Help", the Gems find out that Peridot is using the hub in order to contact The Homeworld, specifically Yellow Diamond, causing many of the TVs on Earth to intercept the message. The group travels there by warping with Lion, since the warp pad is still destroyed. The Gems find a tower crudely assembled out of pillars and slabs salvaged from the ruins. Garnet, worried that Sugilite will go out of control again, fuses with Pearl to form Sardonyx. Sardonyx carefully destroys certain pillars, rendering the hub inactive. The next day, they find the tower reactivated, so Pearl and Garnet form Sardonyx to disable it and stop the transmission. When Steven and Amethyst stake out the hub though, they discover that Pearl was the one reactivating the hub. When Garnet found this out, Sugilite was formed again, demolishing the tower with a single punch.

Trivia

 * A floating chunk of crystals are seen in the center of the first floor of the hub. Their function or relation to the hub is currently unknown.
 * The hub was shooting beams of energy into space in a similar fashion to how other Gem temples shot beams of energy into space while being activated or destroyed (such as the Pyramid Temple).
 * The energy beams could be a visible manifestation of the messages it is sending.
 * The place was, according to the looks of it, abandoned by the Gems long ago, similarly to how the Lunar Sea Spire was abandoned before Steven accidentally sank the temple into the ocean.
 * This is one of the few places to have its Warp Pad destroyed (in this case by Sugilite).
 * It is powerful enough to send a message all the way to the Gem Homeworld.
 * This is where Amethyst sung her first ansolo song, "Tower of Mistakes", in the episode "Cry for Help".
 * It was destroyed by Sugilite in the episode "Coach Steven", but rebuilt by Peridot and later Pearl in "Cry for Help" before it was finally destroyed again by Sugilite in the same episode.
 * A cactus in the shape of Peridot is next to the hub.