The Five Great Mountains 五岳 (Wǔyuè) are: 东岳泰山 (east), 西岳华山 (west), 南岳衡山 (south), 北岳恒山 (north), 中岳嵩山 (center). Note that south and north both read Héng Shān but use different characters (衡 vs 恒).
history
Mt. Heng 恒山 is famous for the Hanging Temple (悬空寺 Xuánkōngsì), a wooden monastery built into a cliff face over 1,500 years ago.