PS4 Mass Effect Legendary Edition
Fifty thousand years ago, the Protheans were the only spacefaring species in the galaxy. They vanished in a swift "galactic extinction." Only the legacy of their empire remains. They are believed to have built the mass relays and the Citadel, which have allowed numerous species to explore and expand throughout the galaxy. Prothean ruins are found on worlds across the galaxy.
While surprisingly intact for their age, functioning examples of Prothean paleotechnology are rare. Time and generations of looters have picked their dead cities and derelict stations clean.