The oldest surviving observatory in China sits in an unassuming spot in Dengfeng, in Henan, and it makes astronomy look more like architecture. The Gaocheng Astronomical Observatory was built in 1276 under the Yuan dynasty by the astronomer Guo Shoujing, who designed a stout stone tower about 9 metres high with a long stone scale running north from its base. The tower was a giant gnomon: the sun cast a shadow along the scale, and by measuring its length at noon through the year, the astronomers could fix the solstices and the length of the year with remarkable accuracy. The calendar that Guo helped create was in use for several centuries.
The site is older than the tower, because this part of Henan was considered the centre of the world, and a much earlier gnomon here is credited to the Duke of Zhou, a figure from over three thousand years ago. The observatory forms part of the Dengfeng group on the UNESCO list, along with the Shaolin Temple's pagoda forest, the Songyang Academy and the Han que gates. It is a good reminder that Chinese science and religion were intertwined with ideas of order and the cosmos.
You will find the countryside dry and open, with wheat fields, walnut trees and the bare ridges of Mount Song to the north. Songyang, a town of about 60,000 people 12 km away, has fuel, food and hotels. The roads are good, though trucks and local traffic make riding a slog at times. Foreign riders should check carefully on licensing before planning to ride in China, since regulations are strict and enforcement is firm.
Spring and autumn are best, and clear winter days can be sharp and bright. Take a moment at the tower to look at how the shadow falls, and read the small museum signs if you can. The temperature on the plateau drops sharply at night, and in summer the afternoon heat is considerable. Henan food is built around wheat, so a bowl of hand-pulled noodles or a steamed bun filled with pork will refuel you better than a snack bar. The best light for photographs is late afternoon, when the stone glows warm.