An unexpected survivor marooned amid the high-rises, the Ancient Observatory (古观象台, gŭguānxiàngtái) is a charming surprise, tucked in the southwest corner of the Jianguomen intersection, beside the Jianguomen subway stop. The first observatory on this site was founded under the orders of Kublai Khan, the astronomers’ commission being to reform the then faulty calendar. Later it was staffed by Muslim scientists, as medieval Islamic science enjoyed pre-eminence, but, bizarrely, in the early seventeenth century it was placed in the hands of Jesuit Christian missionaries. The Jesuits, a small group led by one Matteo Ricci, arrived in Beijing in 1601 and astonished citizens and the emperor with a series of precise astronomical forecasts. They re-equipped the observatory and remained in charge through to the 1830s. Today, the building is essentially a shell, and the best features of the complex are the garden, a placid retreat, and the eight Ming-dynasty astronomical instruments sitting on the roof, stunningly sculptural armillary spheres, theodolites and the like. The small attached museum, displaying early astronomy-influenced pottery and navigational equipment, is an added bonus.