The Black Dome from within.

The Black Dome dominates the skyline of Osirion's capital, Sothis. It is the remains of the carapace of a uniquely gargantuan scarab beetle that has been modified to house the royal palace and the estates of many of the city's noble elite. The shell long predates Sothis, and according to legend (backed by the lore of the cult of Nethys), was part of Ulunat, a spawn of Rovagug who emerged in Casmaron at the Pit of Gormuz and laid waste to northeastern Garund before being killed by Nethys shortly before he became a god. Ulunat's blood was said to inspire springs and oases and young Sothis formed around the husk. The interior of the shell is decorated with magical faerie fire constellations. The Black Dome houses the Palace of the Forthbringer, the Council of Sun and Sky, the Sothis Exhibitory, Menetnashté's Orrery, and the Shepeskan Grove of druid-tended saplings.[1]