Volo's Student's Guide to Sigil East
Sigil East is a suburb of the City of Sigil in which Sigil Prep is located. How a completely contained city with no outlying areas has a suburb is sort of difficult to explain, but in fact, Sigil East is a sub-dimension within the sub-dimension in which Sigil is located. Entering Sigil East is done just east of the Clerk's Ward. It's up to you to determine what's "east" in a ring-shaped city.
There are a number of things to occupy a college kid on the go. As Sigil wards go, Sigil East is pretty safe. Wander into the city proper only if you're looking for trouble. Or better booze. And a lot of intoxicants are illegal in Sigil East that flow like water in the rest of the city. Granted, water flows better in Sigil East, so it balances out.