A Gateway is a ring-shaped machine that works as a means of FTL Travel. It opens up a portal which acts as a means of transport through which sapients can see the other location in spacetime on the each other side. The FTL Signals by which they operate like an intergalactic network use all manner of mediums, such as Subspace or Hyperspace. Some such technology is located in Sol system and even on Earth and Mars. It was left their by various aliens who visited Earth. Often they are also used for the purpose of time travel and multiverse travel. They can both be placed on the surface of a planet or in the vacuum of space.