First City was a municipality on the planet Ardana. It was one of the planet's three largest cities, along with Droxana and Lejico, with a population of three billion. First City was a main tourist center because of its location relative to the Cloud City of Stratos. Following the abandonment of Stratos in the late 23rd century, many of that city's artworks and other cultural artifacts were transferred to the museum in First City.

When Stratos's anti-gravity engines began to fail in 2377, First City was threatened; however, the Starfleet Corps of Engineers was able to maneuver Stratos away from the population center. (CoE eBook: Signs from Heaven)

The three billion figure seems impossibly high for a single city, and is likely a misprint for "three million".