Ralsko is a town (město) in Česká Lípa District, in the Liberec Region, Czechia. Ralsko lies at 331 m above sea level. It has 2,220 inhabitants (2024). The nearest city is Mladá Boleslav, 21 km to the southeast. Among the landmarks around are Bezděz Castle (7.9 km), Kost Castle (26 km) and Houska Castle (16.6 km). Among the natural features are Velká Buková (3.5 km) and Horní Sedlo (26 km).