Sigil

Sigil, also known as the City of Gates and the City of Doors, is a city-state and the suppoed center of the multiverse which includes the prime material plane and all other known planes according to some forms of the Great Wheel Cosmology.

People coming to Sigil from the Prime Material Plane are often treated as clueless inferiors by the planar elitists who dwell there. They are thus widely referred to as "the Clueless", or more charitably, as "Primes". It is highly recommended that planewalkers new to Sigil employ a guide, known locally as a "tout," lest they be taken advantage of or mugged. Such guides can be little better themselves, though, either serving to persuade a traveler to the side of their faction or simply robbing their "customer" once their back is turned.

Government
The ruler of Sigil is a mysterious entity known simply as The Outsider. The Outsider is sometimes seen in Sigil as a floating plain-looking young human man with short brown hair and black eyes, wearing a brown coat, faded gray pants and black boots.