Holy Terra ( Earth ), SOL SYSTEM
The planet of origin of mankind and the centre of it's civilisation for 40,000 years. It is here that the emperor first walked amongst men. It is from here that he began his great crusade to unite the scattered colonies of man, creating the Imperium of Man, encompassing a billion worlds. It is here, today, his moratl body remains encased in the Golden Throne.
The surface of old terra has completely changed in the 30,000 years of mans' progress. Two massive edifices nearly cover the entire surface. The northern continent is covered by the massive structure of the Imperial palace, which amongst other things also contains the Golden Throne. The Southern continent is covered by the Eccleasiarchial Palace which competes with the imperial palace in size and majesty.
Unusually for a spacemarine chapter, the Imperial fists, descendants of those who defended the imperial palace against the hordes of Horus, originally had their fortress base also on terra.
The astronomicon is based within the deep vaults carved in to the Himalayan mountains, the highest on terra. This beacon was created by the psychic might of the emperor and is constantly strnghthened by the ritual soul binding of hundreds of astropaths whose psychic power feeds the strength of the beacon. The safety of navigation through the warp for humans is entirely dependant on this beacon as the navigators in every spaceship use the beacon as a source of reference..