Through the Multiverse
Sigil is the city of portals, it is the link that connects all other worlds and demiplanes together.
editA short history of Sigil.
Sigil is the center point of the multiverse, touching every layer of every major plane, and most demiplanes. It is a great city, taking weeks to walk across it, only to end up where you started. It is one of the only truly neutral grounds, where a devil and an angel could sit side by side discussing philosophy. All through history, it has been protected and governed by a mysterious entity known only as the Lady of Pain, a being of immense power who has on more then one occasion killed a god for endangering the neutrality of Sigil. Roughly 1000 years ago, a great disaster occurred, resulting in the death of many of sigil’s citizens, and throwing the city into disarray.