The largest religious building in the world is Angkor Wat, a Hindu Temple in Cambodia built at the end of the 11th century.

Angkor Wat (Khmer) is the largest Hindu temple complex and the largest religious monument in the world. The temple was built by the Khmer King Suryavarman II in the early 12th century in Yasodharapura (Khmer, present-day Angkor), the capital of the Khmer Empire, as his state temple and eventual mausoleum. Breaking from the Shaivism tradition of previous kings, Angkor Wat was instead dedicated to Vishnu. As the best-preserved temple at the site, it is the only one to have remained a significant religious centre since its foundation – first Hindu, then Buddhist. The temple is at the top of the high classical style of Khmer architecture. It has become a symbol of Cambodia, appearing on its national flag, and it is the country's prime attraction for visitors.

Angkor Wat combines two basic plans of Khmer temple architecture: the temple mountain and the later galleried temple, based on early Dravidian Architecture, with key features such as the Jagati. It is designed to represent Mount Meru, home of the devas in Hindu mythology: within a moat and an outer wall 3.6 kilometres (2.2 mi) long are three rectangular galleries, each raised above the next. At the centre of the temple stands a quincunx of towers. Unlike most Angkorian temples, Angkor Wat is oriented to the west; scholars are divided as to the significance of this. The temple is admired for the grandeur and harmony of the architecture, its extensive bas-reliefs, and for the numerous devatas adorning its walls.

The modern name, Angkor Wat, means "Temple City" or "City of Temples" in Khmer; Angkor, meaning "city" or "capital city", is a vernacular form of the word nokor, which comes from the Sanskrit word nagara . Wat is the Khmer word for "temple grounds", derived from the Pali word "vatta". Prior to this time the temple was known as Preah Pisnulok (Vara Vishnuloka in Sanskrit), after the posthumous title of its founder.