The planet of Lessek (Ilojan transliteration: Lesek) was an otherwise uninhabited rasgălor (outworld) of the Cardassian Union that was home to a small planetside and orbital shipyard complex left over from the days of the Federation-Cardassian War. (Star Trek: Sigils and Unions--The Thirteenth Order)
Some areas of Lessek are known to possess mountains and a system of foothills radiating from the mountain ranges.
At the start of the Dominion War, the training wing of the Cardassian Guard--the Vigilance Corps--intended to use the planet as a base for survival training, and began construction on a small camp approximately seventy-five kilometers away from the existing planetside shipyard. When the Dominion took more desirable Cardassian holdings like the Monac system for their own construction efforts, the Cardassian Guard reopened the Lessek drydocks for what little repair and construction they could manage for their own ships, which typically took last priority in the Dominion repair queue.
When the Vigilance Corps abandoned the planet, a large cache of military supplies, including weapons, uniforms, and other soldiers' gear was left behind. The fact that the Dominion did not catch on to this "error" suggests that it was done on purpose by distrustful members of the Cardassian military with the idea of keeping one up on the Dominion.
Sure enough, four conspiring guls became aware of the stash and beginnings of a training camp, and chose Lessek as the location to build a hidden base. At the Lessek camp, the four guls brought prisoners captured from Starfleet and kept them in a hastily-constructed set of buildings reminiscent of mid-20th-century construction. When they offered these soldiers the chance to join the Cardassian Rebellion, the prison camp converted into a rebel base. (The Thirteenth Order)