Prasat Prei is spelt Prasat Prey, too. The name means "sanctuary in the jungle". The simple structure, though located just 100 metres north to Angkors Grand Circuit road, is a completely untouristed temple in a peaceful surrounding. The side road leading to it begins opposite the southern side road to Preah Khan's east gate. So it is really easy to find Prasat Prei.
Prasat Prei is not of specific artistic interest. Like many others, it is a typical temple in the Bayon style of the late 12th century. The major attraction is its location on a small natural hillock.
In front of the main sanctuary there are remains of an east gate, a very simple and half-ruined Gopuram structure. Inside the relatively small compound surrounded by a laterite wall, you will see the vestiges of a library in the south-east corner, too. The Prasat tower and its adjoining Mandapa antechamber, which are restored, have some well-preserved Devatas or Apsaras on their outer walls and lintel carvings, too.
Do not miss to visit the much larger contemporary temple structure 200 metres further north. It is of a similar name, Banteay Prei. Probable links between these two temples are not yet cleared up.
The morning is much better for a visit than the afternoon. A ticket is not necessary to enter the temple compound, but you will need it at other temples in this area and for using the Grand Circuit road when starting from Siem Reap.