The Assumption of an Astronomical Platform in Cambodia of the VII–VIII Century. A Talk by Olivier de Bernon



The circular structure of Choeung Ek, hardly discernable at ground level is, however, easily identifiable from the sky.

Composed of the remains of a ditch about 10 meters wide, this structure forms a perfect circle of some 760 metres in diameter in the center of which a cruciform terrace has been found. The discovery of charcoal at several characteristic points allow us to date the construction of the round structure of Choeung Ek and its abandonment between the middle of the seventh century and the middle of the eighth century.

This structure has been associated with the “round cities” of Cambodia or Thailand, but it differs in all respects.

Near Choeung Ek, there is the largest concentration of ceramic kilns in Southeast Asia, but no sherds in ditching. It can therefore be said that the structure was abandoned before the establishment of the ceramic industry.

This structure forms a horizontal “natural balcony” that slightly dominates an open landscape, consisting of a vast “lake” (pịṅ). Since this “natural balcony” was not originally exactly circular, the “engineers" of Choeung Ek had to proceed in the seventh century with significant and technically complex development work: flattening some plots or, conversely, enhancement and consolidation of the rounding.

As no urban, agricultural, hydraulic, military, or artisanal necessity could have given rise in the seventh or early eighth century to the construction of a monumental ditch defining a perfectly circular circle of 780 metres in diameter, we proposed to adopt the research hypothesis that Choeung Ek’s round structure was able to respond to a ritual necessity for momentary use, or that it constituted an astronomical measuring instrument. In this last hypothesis, the circular canal could have served as an artificial horizon intended to favor azimuthal sights intended for astronomical observations.


Dr Olivier de Bernon holds a PhD in Philosophy and a PhD in Asian Studies. He has run a manuscript conservation project in Cambodia since 1990 and is a member of French School for Far Easter Studies (EFEO) since 1991. He has been in charge of King Norodom Sihanouk’s personal archives since 2004 and was named General Curator and Chairman of National Museum of Asian Art – Guimet in 2011–2013.

Date: Friday 20 December 2019
Time: 7.00 p.m.
Place: The Siam Society, 131 Asoke Montri Rd, Sukhumvit 21

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