Hestobyll was the capital city of the world Byllura. It was located on a series of terraces that were crafted from a large river delta by a team of Galactic Republic engineers. During the Republic Dark Age, Hestobyll served as the capital of the Dyarchy, a Sith state headed by the twins Dromika and Quillan, and a fleet of Dyarchy battleships was contructed inside secret hangars beneath the city's reflecting pools.