Mass Relay

Mass Relays are mass transit devices scattered throughout the Milky Way in the Mass Effect Universe. They form an enormous network allowing interstellar travel. A mass relay can transport starships instantaneously to another relay within the network, allowing for journeys that would otherwise take years or even centuries with only FTL drives.

Like the Citadel, the Protheans were given credit for its creation but they were actually created by the Reapers.

See also: Mass Relay