Guānxīng Tái Observatory
Sōng Shān & Dēngfēng
In the town of Gàochéng, 15km southeast of Dēngfēng, is China's oldest surviving observatory. In 1276 the emperor ordered two astronomers to chart a calendar. After observing from the stone tower, they came back in 1280 with a mapping of 365 days, five hours, 49 minutes and 12 seconds, which differs from modern calculations by only 26 seconds.