With the mass of a small moon and a longitude of 1622 kilometers, The Imperial Throne City is the Largest Structure made by mankind (6 times larger than Anubis Station). It is said that it affects the weather and the tides of planets if it gets in goestationary orbit.
Legend says that after a construction period of 128 standard years, her Maiden Voyage was inagurated in the Golden Age of Invention by Emperor Saudir IV and it was intended as the Imperial vessel for diplomatic travels across the Old Empire.
After the terrorist Nuclear attacks by Black Zero on the ThroneWorld of Ceres at the time of Seurat the Wise, for security reasons the Emperor, all his court and staff were located in this monolithic Starcruise (it took then the name of Throne-City, but officially Ceres still is ThroneWorld).
Many varied estimates have been made regarding the workforce needed to construct the Great Starcruise but all Xeno-archeologist and historians coincide that it was built around a large asteroid (because of the subterranean cave system under Tyrona Forest in the midsection of the ship) and that it's energy source derives from a Micro-Black Hole of the type that has been proposed to have formed during the Big Bang (primordial black holes).
The Imperial Throne City current course circles the Core Worlds of the Inner Ring of the Empire and is always escorted by the Superdestroyer HMS Apocalypse an two Mark II, the HMS Chimera & the HMS Jörmungandr.