The Five Great Mountains 五岳 (Wǔyuè) are: 东岳 Tài Shān (east), 西岳 Huà Shān (west), 南岳 Héng Shān 衡山 (south), 北岳 Héng Shān 恒山 (north), 中岳 Sōng Shān (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.