The Citadel is the only Obelisk we know of that isn’t surrounded by a continent. Instead, it is surrounded by a port which has arcane tubes. These tubes lead underground to a megastructure big enough to be an entire country.
Initially closed off, once the Elves arrived here, they found the Keepers. These crab like creatures protect and maintain the underground megastructure. They showed the Elves the basics and slowly started to unlock sections of the Citadel once more of the population from Gnomes and then Tieflings and then other races started to come in. It is believed that we have explored and inhabited the entire citadel.
Currently, the Citadel is home to the Council. There are also shops and residential districts and entertainment districts scattered throughout the different levels. While walkways and paths exist to different levels. There also exists and arcane system of tubes which transport people and cargo from location to location.