Rassilon's Foundry

Rassilon's Foundry was an ancient stronghold of the Time Lord Rassilon where he worked on his technological secrets during the distant past of the planet Gallifrey.

It was a secret hiding place located in the wastelands and protected by being shifted one second into the future along with a reality lock. The Foundry made use of dimensional technology making it larger on the inside then it appeared externally. Within its chamber, Rassilon tampered with Gallifreyan physiology in order to give them life after death - a secret that only the Vampire's possessed at the time.

The Foundry contained many technological wonders that were later used by the Time Lords such as a statue of Nemesis to the De-mat Gun. There were even star systems trapped within the structure which contained civilizations that Rassilon felt were a threat to him and included the Divergence. (BFA: Zagreus)