The oldest extant bridge of China is a single span stone arch bridge -- Anji Bridge in Zhaoxian County of Hebei Province, built in the Sui Dynasty (581-618). Also known as the Zhaozhou Bridge with a history of about 1,400 years, it is reputed as The First Bridge Under Sky.

It is a single segmental stone arch, composed of 28 individual arches bonded transversely, 37.02m in span and rising 7.23m above the chord line. Narrower in the upper part and wider in the lower, the bridge averages 9m in width. The main arch ring is 1.03m thick with protective arch stones on it. Each of its spandrels is perforated by two small arches, 3.8m and 2.85m respectively in clear span, so that flood water can be drained and the bridge weight is lightened as well.

The Anji Bridge has a segmental deck and the parapets are engraved with dragons and other animals. Its construction started in the 15th year (595) of the reign of Kaihuang and was completed in the 1st year (605) of Daye's reign of the Sui Dynasty.

The bridge, exquisite in workmanship, unique in structure, well-proportioned and graceful in shape, and meticulous yet lively in engraving, has been regarded as one of the greatest achievements in China. Great attention and protection have been given to it through successive dynasties.

The Anji Bridge is by far the earliest and best preserved stone arch bridge in the world. In 1991, it was named among the world cultural relics of civil engineering, which indicates that the Anji Bridge is equally famous as the Eiffel Tower in Paris, the Panama Canal and the Pyramid in Egypt.