Little is actually known about these strange monuments of a bygone era. The Conqueror's Brigade has pieced together that three are known to exist and they seem to be the banners of the Northern, Middle, and Southern kingdoms (map) of the the empire of the City State of the Invincible Overlord.

During the Maztican campaign the party recovered the southern obelisk from the Bomak Jungle of the Pezelac and later contended with Alaginzera and other githyanki aboard the Nautiloid spacecraft who stole and hid it in a cave until Soris and Dark’n found the lair, slew her and recovered the obelisk. It was finally taken to Tukan where it remains today as the symbol of the seat of power of the southern kingdom’s new capital. When the obelisk was recovered, found with it was a star ring that Soris defiantly held from Kalanan for a time before eventually trading it to him for a ring of shooting stars among other terms of a political negotiation.
Later, at the beginning of the King of Swords adventure (Episode 1, recording 3, minute 29), Kelanen returned to Honorable John the ring of the southern obelisk, bestowing with it also the scepter of the northern obelisk at Modron, and the circlet of the middle kingdom of Kalandria. These he was instructed to place in the care of the clergy of the Cult of Swords in each location to ensure the loyalty of the kings of those nations… John, as a resident of the CSIO and the middle kingdom, and high priest of the cult, was honored with being the keeper of the circlet.

During the King of Swords, Episode 2, John traveled west of the CSIO to the middle kingdom obelisk in Dearthwood and used the circlet to activate it’s power and travel to the Dead Lands. Whatever other powers the obelisks may or may not possess, they seem to be Portals…

It is also known to John that the names of the Giant and Dragon King lines of old are carved into the middle-kingdom’s obelisk.