The modern name "Thommanon" is derived from "Dhamma", which is the Buddhist teaching, and "nanda", meaning "supreme wisdom". "Thommanon" is stressed on the first and on the last syllable.
The temple is located just north of the Small Circuit road running from the Royal Palace in Angkor Thom to the east. Thommanon is outside Angkor Thom, close to the west bank of the Siem Reap river. It was built in the early twelfth century, in the early phase of the style of Angkor Wat.
Thommanon is a small compound and a flat temple (without upper levels of rooms). It has only one Prasat, with a cruciform ground plan. The core temple structure, consisting of the Prasat tower with a preceding Mandapa hall, connected by am Antarala passageway, is of considerable size and elegant classical Khmer design in sandstone, and it is well preserved. Gopuram gates in the east and west and a library building in the south east corner are in a good condition, too, after the complex underwent restoration in the 1960s by French archaeologists, who supplemented the broken roof by adding concrete ceilings.
The highly stylized Devata goddesses (often called Apsaras) of the outer walls are of excellent quality. The Devata figurines have flower crowns, necklaces, armbands, belts and ankle bands. They are well-known for their complex mudras, particularly those hands gripping flowers and holding the ring and middle fingers against the thumb. The Devatas at Thommanon depict two completely different styles of sampot skirts, besides those in the Angkor Wat style others resemble those of much earlier periods.
Superimposed pediments are decorated with reliefs, too. Inside the Mandapa and the Antarala are well preserved lintels above doorways, but not easily to study because of the darkness. With a torch you can see Vishnu on halfbird Garuda and Indra on elephant Airawata. Other interesting panels show the death of monkey-king Valin, which is a topic of the Ramayana legend, demon-king Ravana shaking Mount Kailash to disturb Shiva's and his followers meditation, Krishna lifting Mount Govardhana in order to protect his followers from Indra's rainstorm. The western Gopuram, at its south side, depicts Shiva meditating (as Mahayogi) and, at the north side, the churning of the milk ocean, and Vishnu on Garuda fighting against an Ashura demon.
Thommanon is often paired with the nearby Chau Say Tevoda just across the Small Circuit road, as both were built by Suryavarman II, and appear almost similar in style.
There is no specific most recommendable time of the day for a visit of Thommanon. The morning may be slightly better, but in the early afternoon the bas reliefs at the western Gopuram will be exposed to the sunshine. Usually, the Angkor ticket will not be checked here, anyway, you need it for the Small Circuit.