A remote trading town
Idathren is an out-of-the-way town, only frequented by trade ships travelling along the Thirr. The population is mixed, with roughly 1/3 outlanders, 1/3 poor Velothi, and 1/3 other dunmer. The main attraction of the town is the Savri's Cornerclub, a meeting place for all kinds of people, doing all kinds of (legal or illegal) things.
The Mages Guild established a research station in the town relatively recently, to study Lake Andaram and the nearby Daedric Ruins. The location of this minor, temporary guild hall is an old guard tower, repurposed for the duration of the excursion.