Hestobyll functioned as the main city and capital of the world called Byllura. A group of Galactic Republic engineers constructed this city on several terraces carved out of an expansive river delta. In the era of the Republic Dark Age, Hestobyll became the capital for the Dyarchy, which was a Sith nation ruled by the twin Sith Lords, Dromika and Quillan. A fleet of Dyarchy battleships were built in concealed hangars situated below the reflecting pools of the city.