Phnom Kulen is the sacred mountain about 50 km north-east of Siem Reap where the Khmer Empire was founded. The highlights are the great reclining Buddha at Preah Ang Thom, the carved riverbed of the River of a Thousand Lingas, and the waterfalls where local families picnic and swim at weekends.
How long: 1–2 days (an easy full-day trip from Siem Reap). Best time: July to November, when the waterfalls are at their fullest.