The Ancient Observatory, Beijing

A squat brick platform stands on what was the line of the city wall at Jianguomen, and it worked as an observatory from the Ming period into the twentieth century, one of the longest continuous runs of astronomical observation anywhere. On the roof sit large bronze instruments cast in the seventeenth and eighteenth centuries, among them armillary spheres, a celestial globe, a quadrant, a sextant and an azimuth theodolite, several designed by Jesuit astronomers employed at the court and mounted on cast dragons and cloud scrolls that are as much sculpture as engineering. The courtyard halls below cover older Chinese astronomy, constellation maps and the making of calendars.

What you actually see

• The roof instruments - bronze armillaries and globes on dragon supports, out in the open air.
• The Jesuit designs - European instrument forms rebuilt in Chinese bronze in the 1670s.
• The star charts - Chinese constellation maps and calendar records in the courtyard halls.
• The wall line - the platform stands on the old city wall alignment, now ringed by traffic.

When to go

Open daytime hours through the year, and quiet almost always, which is unusual for central Beijing. Spring and autumn suit the open roof platform, since the instruments stand outdoors with no shade or shelter, so skip summer afternoons and the coldest winter days. An hour is enough unless you read every label.

Honest expectations

It is a small site and the exhibition halls are dated, with brief English labels that assume knowledge you may not have. Not everything on the platform is original and the signage is not always clear about it. Flyovers and office towers press right up to the walls, and the traffic noise never stops.

Nearby

The Temple of Heaven is a short metro ride southwest, and the eastern city wall park is nearby.