The Pyramid of Kamaria is the burial place for the Pharaoh Kamaria the Brazen, the only Osirian ruler to have openly worshiped the god Rovagug. It sits on the outskirts of the southern Osirian city of An, and dominates the settlement's southern skyline. The upper levels of the pyramid have long been cleared-out by tomb robbers, but are the home of a large cult of Rovagug; even they do not enter the lower trap-infested levels, however. The pyramid's central shaft dominates these dungeons, and it reaches all the way down to the Bloodcleft in the Darklands realm of Nar-Voth. A tribe of degenerate grimlocks is known to dwell near the shaft's base, and they occasionally trade strange artifacts and monstrous pets for slaves and food with the cultists above.123
The first major task of pharaoh Gebessek IX, after the assassination of his despised mother, was to exterminate every Rovagug cultist in the pyramid, the entire population of the city of An, and seal the sublevels of the pyramid with potent magic and wards.
In the reign of pharaoh Remeses IV the cult of Rovagug sought to return to the pyramid. Remeses IV initially dealt harshly with the cult, now known as the Cult of Rovagug Made Visible and led by Eshemel Bhalloc, but later decided it was better to allow them to re-establish themselves within the pyramid rather than have them organise elsewhere in secret. This policy has been followed by subsequent pharaohs.4
Paizo published a major article about the Pyramid of Kamaria in Chapter 4 of Dungeons of Golarion.
For additional as-yet unincorporated sources about this subject, see the Meta page.