- “Perhaps not a planet? Could place a space station with powerful mass effect shields.”— Mordin Solus.
The Collector Base was a massive space station located in the Milky Way Galactic Core, and was the capital, as well as "homeworld", of the Collectors. Constructed after the first rate of Collectors was converted by the Reapers, the Collector Base has, for billions of years, served as the headquarters of the Collectors of the Cycles, with three cruisers attached to it for use by their legions. This is where the Collector General was housed, and where the construction of each cycle's Reaper was carried out. Near the edge of a black hole's event horizon, the Collector Base utilized Reaper technology and powerful mass effect fields to keep it from falling into the black hole's inescapable gravity vacuum. Until 2185 CE, the Base's existence was a well kept from the rest of the galaxy, with the galaxy assuming the Collectors had a homeworld.
During the final days of the Collector campaign, the Normandy squad launched a daring assault on the Collector Base: a feat nobody had ever achieved before them. Due to the Collectors not possessing any actual defensive strategy for when their Base was attacked, the squad was able to successfully overload the reactor, destroying the Base and all the Collectors on it.