The City Lord's Mansion occupied the prime real estate of the inner city, located near the eastern district.
The Lord of Great Plain City wasn't an innate powerhouse like Morning star Magus but certainly wasn't a simple figure either. His invitation to Aizen tonight was undoubtedly to discuss the distribution of resources and territories within the city.
No matter how dominant the Heavenly Demon Clan had become in Great Plain City, it remained subject to the oversight of the City Lord's Mansion and the constraints of the imperial government. As long as the Skywind Dynasty stood, this unwritten rule persisted. The government held the legitimate authority, and all other factions—no matter how rampant—had to show deference. To challenge or supersede the government's authority would be tantamount to rebellion.
Even though the Skywind Dynasty was in decline, no faction dared to be the first to openly rebel.