Known as the "River of a Thousand Linga" (a lingam is a phallic symbol representing the Hindu god Shiva), Kabal Spean lay undiscovered by Westerners until a French researcher stumbled across it only recently. Dating from the early 11th century, the relief carvings that line the streambeds are said to purify the water before it fills the reservoirs (called barays) of Angkor. It's the journey here that's really interesting -- on some rough roads through rural villages north of Banteay Srei -- and there's a fun forest hike (about 30 min. to the first waterfall). Khmers come here to picnic, and it's a good spot to swim or follow the path that trips along at brook side; from there, you can view the many carvings in relief on the banks and creek bed.