Kbal Spean is 44 km far from Angkor wat. It is possible to visit both in 1 day. You need to travel by car. 
The area includes a series of stone carvings in sandstone blocks of riverbeds and riverbanks. It is often called the “Valley of 1,000 Lingas” or “The River of thousands of Lingas”. The motifs for the stone carvings are predominantly numerous lingams (phallic symbols of the Hindu god Shiva), described as neatly arranged bumps that cover the surface of a sandstone rock and lingam design – yoni. There are also various Hindu motifs, including descriptions of the gods Shiva, Vishnu, Brahma, Lakshmi, Rama, and Hanuman, as well as animals (cows and frogs).
How to get there: Located about 18 km north of the Queen’s Palace.
You can go for Tuktuk 25-30 dollars, buses 35-40 or minibuses 35-45 dollars to get there.