Csaplar was the capital city of the planet Csilla and the Chiss Ascendancy. Csilla was the homeworld of the sentient, near-human Chiss species. By the time of the rise of the Galactic Empire, most of the city was located underground, well below Csilla's icy surface.
The Csaplar spaceport was one of few populated aboveground locations in the city. Most of the other aboveground populated areas were either government business or trade-related, and in either case were aboveground mainly to present the false appearance to off-world visitors that Csaplar and Csilla were far more populated than they were in reality. To create this illusion of a thriving city, a few hundred people, who were rotated frequently, would be present in the aboveground areas of Csaplar at any given time. In addition traffic, light and heat sources were maintained to imitate everyday life of the official population of 7 million. All this effort was made to mislead potential enemies into wasting a massive attack force on a city that was essentially empty.