Gallifrey is the home planet of the Time Lords. From there, they ruled over time for millenia, until they were brought down by the Daleks. Gallifrey was the site of an untempered schism, a 'hole in time' created by Dialga that gave the Time Lords time powers and also their TARDISES. Gallifrey was the hub of time travel for many years, and was a place of peace. The trees were golden and the sky was red, and there was no trouble or disease or death. Gallifrey was the shining crown jewel of the Galaxy, adored by the higher races and admired by the lower ones. Only one race despised the Time Lords - the race that despises everything - the Daleks. The Daleks declared war on the Time Lords and, despite their best efforts, the planet was ravaged. Rassilon planned to save Gallifrey by bringing it out of the Time Lock and towards Earth, but the Doctor and the Master sent him packing and Gallifrey was returned to the War. The version of the Doctor from the War used a Time Lord relic to obliterate everything in the war, finally destroying the devastated planet.