Sorraia is the capital circ-city of Asura. Currently the biggest circ-cirty, it is the only one which has a 15 level spire at the center of the Temple Dome. This city is also the area where the leader lives within the spire.
Sorraia is also the technological hub for aerial vehicles and most weapons. Most of the bio-engineering experimentations also take place in Sorraia which is why one specific dome has been converted for just that purpose.