Tu'narath is the central city of the Githyanki in Dungeons & Dragons. Ruled over by the lich-queen Vlaakith CLVII, it resides in the Astral Plane (or Astral Sea) and is built atop the enormous, world-sized petrified corpse of a long-dead deity referred to only as "The One in the Void". Identification is rather tricky as its face has been chiseled off, though whether this was done by the githyanki or not is unknown.
Vlaakith CLVII quest for godhood involves absorbing the divine spark of "The One in the Void", which elevates her to godhood, as the cost of shattering Tu'narath into several pieces and kills more than half the population in the city.
The 5e book Mordenkainen's Tome of Foes has many details on the place, including some rad art. Apparently Thayan wizards have been trading for the god's petrified organs or some shit.
|The Gith of Dungeons & Dragons|
|Races:||Duthka'gith - Gith - Githyanki - Githzerai - Half-Githzerai|
|Undead:||Kr'y'izoth - Tl'a'ikith|
|Individuals:||Vlaakith CLVII - Zaerith Menyar-Ag-Gith - Zerthimon|
|Places:||Shra'kt'lor - Tu'narath|
|Prestige Classes:||Blackweave Warlock - Ghustil - Gish Mindslayer - Holocaust Warrior - Sword Stalker|
|Adventures:||Incursion - Scales of War|
|Miscellaneous:||Crown of Corruption - Gish - Scepter of Ephelomon|
|The Cosmology of Planescape|
|Inner Planes||Ethereal Plane||Prime Material||Astral Plane||Outer Planes|
|Elemental Planes||Energy Planes||Demiplane of Dread||Plane of Shadow||Plane of Mirrors|
|World Serpent Inn||Tu'narath||Sigil||Demiplanes||Ordial Plane?|