Stráž pod Ralskem (until 1946 Vartenberk; German: Wartenberg (am Rollberg)) is a town in Česká Lípa District in the Liberec Region of the Czech Republic.

The local castle was called Wartenberg (Warte auf Berge meant "guard on the hill" in German).

The modern Czech name of the town Stráž means 'guard'; pod Ralskem refers to its location below Ralsko Mountain.

The highest point is a nameless hill at 407 m (1,335 ft) above sea level (the mountain of Ralsko is located outside the municipal territory).

In 1504, the Wartenberg family sold the estate to Bartholomew Hirschpergar, who rebuilt the medieval Gothic castle into a comfortable aristocratic residence.