---
title: Cheomseongdae
author: Mark Cartwright
source: https://www.worldhistory.org/Cheomseongdae/
format: machine-readable-alternate
license: Creative Commons Attribution-NonCommercial-ShareAlike (https://creativecommons.org/licenses/by-nc-sa/4.0/)
updated: 1970-01-01
---
# Cheomseongdae
_Authored by [Mark Cartwright](https://www.worldhistory.org/user/markzcartwright/)_
Cheomseongdae (Chomsongdae) is a 7th-century CE observatory tower located in [Gyeongju](https://www.worldhistory.org/Gyeongju/), the capital of the [Silla](https://www.worldhistory.org/Silla/) Kingdom of ancient [Korea](https://www.worldhistory.org/Korea/). It is the oldest surviving astronomical observatory in East Asia and is listed as no. 31 on the official list of National Treasures of Korea.
### Gyeongju – [City](https://www.worldhistory.org/city/) of Arts & [Science](https://www.worldhistory.org/science/)
It is believed that the observatory tower, sometimes known as the Cheomseongdae Royal Observatory, was, according to the 13th-century CE *Samguk yusa text, built in the early years of the reign of [Queen Seondeok](https://www.worldhistory.org/Queen_Seondeok/) (632-647 CE), who reigned just before the Silla kingdom would reach the height of its prosperity and go on to control all of the Korean peninsula in 668 CE. The capital at Gyeongju became a centre of [culture](https://www.worldhistory.org/disambiguation/culture/), arts, and science with a particular flourishing in mathematics, astronomy, and astrology. It is likely that the Cheomseongdae tower was the centrepiece of an entire scientific district, such was the importance given to the effect of celestial bodies on human affairs in Korean culture. The name Cheomseongdae may be translated as the 'reverently regarding the stars platform.'
### Design & Function
The granite observatory tower is constructed in the shape of a bottle. Nine metres (29 ft) tall, it was made using 362-5 (scholars cannot agree on the exact number) large stone rectangular blocks set in a circular arrangement of 27 courses. These numbers are significant according to some historians. The number of blocks symbolises the days of the year and Queen Seondeok was the 27th monarch of the Silla kingdom. Further, the small square window of the tower is so positioned that there are 12 layers of bricks above and below it, representing the calendar months. The tower stands on a square base constructed using a single course of bricks. The tower narrows as it rises and is topped by a square platform made from eight long blocks, two on each side. The overall design is thus thought to encapsulate the traditional Chinese worldview of the 'round-heaven, square-earth.'
The tower acted like the gnomon of a sundial. It also has a south-facing window which captures the sun's rays on the interior floor on the spring and autumn equinoxes. Originally there may also have been an armillary sphere (model of celestial bodies) on top of the tower. Astronomy and astrology were an important part of everyday life in ancient Korea, governing such activities as [agriculture](https://www.worldhistory.org/disambiguation/Agriculture/) and giving divine authority to the actions of the sovereign. The science of observation was also highly developed and Silla scientists produced detailed star charts, no doubt, using such observatories as Cheomseongdae.
### Alternative Theories
More controversial theories as to the purpose of the tower are that it was designed to imitate the holy [Buddhist](https://www.worldhistory.org/buddhism/) mountain Mt. Sumeru and was a site of worship and prayers of the state [religion](https://www.worldhistory.org/religion/) at that time. Another theory is that the tower was built in honour of the Mesopotamian goddess [Ishtar](https://www.worldhistory.org/ishtar/) ([Inanna](https://www.worldhistory.org/Inanna/)), who was associated with the heavens and who may have been worshipped by Queen Seondeok. Still another suggestion is that the tower represents the female form and was, therefore, a [temple](https://www.worldhistory.org/temple/) dedicated to worship of the queen, the first female ruler in the history of the Silla kingdom. Lacking any convincing evidence to support such propositions, however, the scholarly consensus remains that the tower was, in fact, an observatory.
This content was made possible with generous support from the [British Korean Society](http://www.britishkoreansociety.org.uk/?utm_source=ancient.eu&utm_medium=link&utm_campaign=ancient.eu).
#### Editorial Review
This human-authored definition has been reviewed by our editorial team before publication to ensure accuracy, reliability and adherence to academic standards in accordance with our [editorial policy](https://www.worldhistory.org/static/editorial-policy/).
## Bibliography
- [Jinwung Kim. *A History of Korea"Land of the Morning Calm" to States in Conflict.* Indiana University Press, 2012.](https://www.worldhistory.org/books/0253000246/)
- [Kyung Hwang. *A History of Korea.* Palgrave Macmillan, 2010.](https://www.worldhistory.org/books/0230205461/)
- [Michael J. Seth. *A Concise History of Modern Korea.* Rowman & Littlefield Publishers, 2016.](https://www.worldhistory.org/books/1442260475/)
- [Portal, J. *Korea: Art & Archaeology.* Thames & Hudson, 2000.](https://www.worldhistory.org/books/0500282021/)
- [Pratt, K. *Korea.* Routledge, 1999.](https://www.worldhistory.org/books/0700704639/)
## About the Author
Mark is WHE’s Publishing Director and has an MA in Political Philosophy (University of York). He is a full-time researcher, writer, historian and editor. Special interests include art, architecture and discovering the ideas that all civilizations share.
## Timeline
- **57 BCE - 918 CE**: The [Silla](https://www.worldhistory.org/Silla/) Kingdom rules in [Korea](https://www.worldhistory.org/Korea/), first as one of the Three Kingdoms and then alone from 668 CE.
- **632 CE - 647 CE**: Reign of [Silla](https://www.worldhistory.org/Silla/) [queen Seondeok](https://www.worldhistory.org/Queen_Seondeok/) in south-eastern [Korea](https://www.worldhistory.org/Korea/).
## Cite This Work
### APA
Cartwright, M. (2016, October 11). Cheomseongdae. *World History Encyclopedia*.
### Chicago
Cartwright, Mark. "Cheomseongdae." *World History Encyclopedia*, October 11, 2016. .
### MLA
Cartwright, Mark. "Cheomseongdae." *World History Encyclopedia*, 11 Oct 2016, .
## License & Copyright
Submitted by [Mark Cartwright](https://www.worldhistory.org/user/markzcartwright/ "User Page: Mark Cartwright"), published on 11 October 2016. The copyright holder has published this content under the following license: [Creative Commons Attribution-NonCommercial-ShareAlike](https://creativecommons.org/licenses/by-nc-sa/4.0/deed.en). This license lets others remix, tweak, and build upon this content non-commercially, as long as they credit the author and license their new creations under the identical terms. When republishing on the web a hyperlink back to the original content source URL must be included. Please note that content linked from this page may have different licensing terms.