ScienceReign of Queen Seondeok (c. 633)

Cheomseongdae Built

In the reign of Queen Seondeok, the stone observatory Cheomseongdae was built in Gyeongju.

Cheomseongdae, Gyeongju — astronomical observatory built under Queen Seondeok
Bernard Gagnon · CC0 · Source

Cheomseongdae stands north of Wolseong in Gyeongju. The Samguk yusa says it was built of dressed stone under Queen Seondeok, and Joseon records date it to 633. It is regarded as the oldest surviving observatory in East Asia.

About 9 m tall, it rises in 27 courses of some 362 stones in a bottle shape from a square base, topped by a frame of stones in the shape of the character 井 (well). A square window halfway up on the south side was probably reached by ladder. Some read the number of stones as the days of the year.

The usual view is that it served to read the heavens for the farming calendar and omens, though others see it as an altar or a symbol. Bunhwangsa (634) and the nine-storey pagoda of Hwangnyongsa (645) also date from her reign.

Show on the map

The map in AD 633

Open the full map

OpenFreeMap © OpenMapTiles © OpenStreetMap contributors

States and rulers at the time: Silla — Queen Seondeok
Places: Cheomseongdae, Gyeongju

People

Queen SeondeokAD 647
monarch · Twenty-seventh ruler and Silla's first queen, under whom Cheomseongdae and the nine-storey pagoda of Hwangnyongsa were built

Before and after

Earlier: AD 631 Building the Thousand-li Wall
Later: AD 634 Brick-imitating Stone Pagoda of Bunhwangsa, Gyeongju

Themes that include this event

Science and Technology HeritageAD 633 – 1861
From Cheomseongdae to the Daedong yeojido — instruments and maps that measured the sky, kept time, gauged rain and charted the land
Intangible and World Heritage2000 BC – 1850
From the dolmens to Namhansanseong on the World Heritage List, from Jongmyo ritual music to ssireum on the Intangible Heritage lists — where each came from and when it was inscribed
Gyeongju57 BC – 1860
Silla’s capital for a thousand years — tombs, pagodas, temples and bells from every age of Silla, and the birthplace of Donghak