Welcome to Ravnica: City of Guilds. Since ages past, the ten guilds of this city have existed, swaying back and forth from peace to war for a time until the Guildpact was created. The document magically enforced the peace between the guilds for over ten thousand years until it was destroyed in order to rid the city of the Vampire Lord known as Szadek. Since then, the city has slid back into its old ways, the guilds lashing out at each other when the need strikes. The ten guilds, while working together, each have a purpose in the city.
The Boros Garrison acts as the police and army of Ravnica. The Selesnyan Conclave is the religious authority. Orzhov Council employs the banks and lawyers. The Izzet League maintains the utility systems and is the innovative center of the city. The Simic Combine are the doctors and bio-engineers. The Gruul clans remain split, half teaching the citizens of Ravnica the ways of nature while the other half yearns to bring the city to the ground so nature can return. The Golgari Swarm fulfills the need for food in the city and keeps the lower levels clean of the dead and rotting. The Dimir, once the opponents of the Guildpact, now act as the spies of the city. The Cult of Rakdos are the jailers, making every citizen of the city second guess any criminal activity. The Azorius Senate acts as the voice of the people and create the laws of the city.
The city never stopped growing until its unification into the Multiverse. Even now the city slowly builds outward, taking land that was stolen by the sea to make room for new homes, buildings, roads, and markets. All manner of things exist here, from mythical beasts and explosive science to dark deals and holy chapels. There is a saying in this city. All Roads lead here because all things can be found here.