Angkor Wat
Angkor Wat is THE temple of Cambodia, the largest religious monument in the world! built for King Suryavarman II in the early 12th century as his state temple and capital city. The largest and best-preserved temple at the site, it is the only one to have remained a significant religious centre since its foundation; first
Hindu, dedicated to Vishnu, then Buddhist. The temple is the epitome of the high classical style of Khmer architecture. It has become a symbol of Cambodia , appearing on the national flag!
Angkor Wat combines two basic plans of Khmer temple architecture: the temple mountain (often said to resemble a pyramid) and the later galleried temples. It is 
designed to represent Mount Meru , home of the gods in Hindu mythology: within a moat, which used to be a home for crocodiles, sadly no longer there due to hunting and an outer wall 3.6 km (2.2 miles) long are three rectangular galleries, each raised above the next.
In the 14th or 15th century the temple was converted to Buddhist use, which continues to the present day. Angkor Wat is unusual among the Angkor temples in that although it was somewhat neglected after the 16th century it was never completely abandoned. Its moat also provided some protection from encroachment by the jungle.
The temple required considerable restoration in the 20th century, mainly the removal of accumulated earth and vegetation. Work was interrupted by the civil war and Khmer Rouge control of the country during the 1970s and 1980s, but relatively
little damage was done during this period other than the theft and destruction of mostly post-Angkorian statues. When you reach the top teir of the structure you notice that most of the religious statues sadly have had their heads removed, these were sold to foreign collectors, some have been returned and now live in the galleries of Phnom Penh .
The temple is very hard to climb (especially in 42 degree heat and flip flops) some of 
the angles are up to 60/65 degrees and the steps little more that an inch or 2 wide! But the views from the top are astonishing. You can also see the temple from a balloon that goes 100 metres in the air; which is great as long as you don’t look down!
The temple has become a symbol of Cambodia , and is a source of great national pride. Angkor Wat has been a part of every Cambodian national flag since the introduction of the first version circa 1863.—the only building to appear on any national flag.