Castlemuir is an ancient fortress, located in a secluded mountain valley at the junction of the Saugreth-Muir and Frostcrown Mountains.

The fortress was built during the era of the Ravinian Empire, and once guarded the junction of the Stoneway and the Oramar Road. The fortress was long thought to be abandoned, but recently became the stronghold of a powerful wizard named Varanthis Melzec.