Angkor Archaeological Park

Passes are required to enter the Angkor area. They are on sale at the front gate for 1-day $20, 3-day $40, or 7-day $60 intervals children under 12 enter for free after showing a passport. The 3-day pass is valid for any 3 days within a week, while the 7-day pass is valid for any 7 days within a month. If you plan on using your 3 or 7 day pass on non consecutive days, make sure to get the newer version, otherwise you may be given an old one that must be used immediately. Cambodians can enter for free — you shouldn't need to buy a pass for your guide or your driver. If you buy a pass in the evening, you can enter the park after 5PM to view the sunset without it counting as use of a day on your pass. The passes are non-transferable. You will have a photograph taken and printed on your pass to make sure they are non-transferable. Regular checks for the pass are performed at almost all sites within the park, so carry your pass with you at all times, and be certain to buy the passes only from the official Apsara Authority counters, not from other vendors, and definitely not second-hand.

Guides can be hired for about US$20 a day and are available for most major languages. Hiring a guide for at least the first day can help you get orientated to the temples and are particularly useful for finding and explaining the bas-reliefs, which can otherwise be rather overwhelming and/or difficult to understand.

"Ancient Angkor", the guidebook that is hawked at every temple, is surprisingly good. Particularly if you are interested in the carvings on the walls and towers, the book will keep you occupied for hours. If you don't want to pay money to hear a local tell you about the temples in broken English this is a good option. Authored by Michael Freeman and Claude Jacques, the cover price is US$27.95 at bookstores. The brand new copy is amazingly sold by vendors at US$7 only - highly recommended. As of Sept. 2012, a vendor in Banteay Srei is willing to sell for US$4 only.

Be sure and get to the temples early. You can enter the park beginning at 5AM; the temples open at sunrise. There are fewer visitors early in the morning, and the sun isn't at full force. Arriving at the temples at 8AM instead of 9AM can make all the difference in staying one step ahead of the crowds.

The temples can broadly be categorized into four groups:

Angkor Wat and Angkor Thom
the grandest temple of all and the ancient capital next to it
Little Circuit
Le Petit Circuit, taking in major sites to the east of Angkor Thom
Big Circuit
Le Grand Circuit, taking in major sites north and further out east
Roluos group
15 km east from Siem Reap along National Highway 6
Outlying temples
located over 20 km from Angkor Wat

You can, of course, mix and match freely, but as distances are fairly long, it makes sense to plan ahead and pick sites connected by road. Most car, tuk-tuk or moto drivers will have an itinerary ready if you don't have one in mind, and their expertise may come in handy for arriving at sites a step ahead of the big tour groups.

other angkor thom sights

The Bayon and Baphuon temples form only part of what was formerly the giant city of Angkor Thom, once thought to hold a population of one million.

In addition to the Bayon and Baphuon temples, the ancient city of Angkor Thom holds a number of other sites of interest:

The Elephant Terrace
The Terrace of the Leper King
Five entrance gates
one at each ordinal compass point and the Victory Gate in the east wall. The western and the northern gate are free from tourists, and climatic. Each of the gates is topped by the face of Avalokitesvara. There is a path on top of the walls, and one along the outside wall, that can be followed to walk from gate to gate. The total walk is around 13km, about 3.5 hours long.
Phnom Bakheng
The first temple-mountain constructed in Angkor, with a commanding hilltop location. Extremely popular and crowded spot for sunsets: allow half an hour for the sweaty hike to the top, and leave early or bring a flashlight for the way back. The final climb to the top of the temple is steep and dangerous at dark. Elephants will carry you to the hilltop for $20 per person as of 2008-11-08, but you still have to climb the temple stairs on your own. Note that the sun does not set over Angkor if seen from here, and any visible temples are in fact quite far away. Also note that you are NOT allowed to climb Phnom Bakheng after 17.30 - hence make sure you arrive earlier. An elephant ride back down the hill will cost $15 per person.
big circuit

In clockwise order, exiting Angkor Thom by the North Gate:

Preah Khan
Jayavarman VII's first capital, before the completion of Angkor Wat. Large and atmospheric, yet somewhat overshadowed by Angkor Wat and Ta Prohm, this temple is partly in disrepair with strangler figs crawling up the walls, but has some excellent carvings and less visitors, and is well worth a visit. The temple is some 3 kilometers north of Angkor Thom.
Neak Pean
Not really a temple, this is an interesting quick stop. It consists of four ponds surrounding a large pond that has a tower in the middle. This tower is accessible on a causeway that cuts across the pond.
Ta Som
East Mebon
Located on what was an island in the now dry East Baray, this is a large, three-story temple-mountain crowned by five towers, like a miniature Angkor Wat. Originally built by Rajendravarman II in the 10th century, many structures are in poor shape, but the temple is best known for its massive restored elephant statues.
Pre Rup
A temple-mountain close to and quite similar in style to East Mebon, and constructed only a decade later. A favorite spot for viewing the sun set into the jungles and rice paddies of the Cambodian countryside.
baphuon

Located to the northwest of the Bayon, the Baphuon is supposed to represent Mount Meru sacred to Hinduism, and was one of the largest and grandest structures in Angkor. Built into the western face of the Baphuon is a giant reclining Buddha, added in the 16th century after the region converted from Hinduism to Buddhism.

Archaeologists had dismantled the Baphuon to perform renovation when they were interrupted by the civil war; the records for piecing the temple back together were subsequently lost or destroyed. Today it is undergoing painstaking reconstruction work, so visitors can only walk across the long terrace leading up to the main structure and around the outside base. Completion is estimated for 2010.

roluos group

The ruins here are from the ancient capital of Hariharalaya, dating from the late 9th century and thus predating Angkor itself.

Bakong
A five-terraced pyramid in the mountain-temple style.
Lolei
An island temple constructed in a baray, now dry.
Preah Ko
The first temple to be built here, dating from the 9th century.