Grand Thesda is ancient. Dating back to the wars of ancients before the documentation of any human kingdoms, it is unknown what built this great city.
Thesda is protected by massive walls that run not only along the edges of the city, but also slice the city into a grid pattern. The districts have been used to separate the peoples of Thesda into easily manageable groups. It has also had the additional bonus of containing any threats to a limited area should they manage to appear within the walls.
The ruling class of Thesda is confined to the inner tiers of the city. Admittance is only permitted for those of noble birth of have earned they way in through other means.