The well-known Zhaozhou Bridge, also known as Anji Bridge or Dashi Bridge, is a large stone-arched bridge located on the Xiaohe River in Zhaozhou County, Hebei Province . It is the largest and oldest stone-arched bridge in the world.

It took 11 years to complete the bridge -- from the first to the 11th year of the Daye reign (605-616) of the Sui Dynasty (581-618). Bridge designer Li Chun built the Zhaozhou Bridge south of Beijing with a stone arch made of massive limestone wedges reinforced with iron. The innovative main arch of the Zhaozhou Bridge curves to form a shallow arch rather than the half circle preferred by Roman engineers at the time.

Li's creativity and ingenuity in producing such a unique design and structure has won the admiration of many people. The Zhaozhou Bridge predates any comparable development in Europe by several hundred years. 

The Zhaozhou Bridge is 50.82 meters long and 9.6 meters wide; the span of its large stone arch in the middle measures 37.37 meters -- the world's largest arch at the time. There is also a smaller symmetrical arch at each end. This kind of structure not only requires less building materials but also makes sluicing during the flood season much easier. The bridge floor is smooth and flat with passages for pedestrians on both sides, while carriages and  carts can move through the middle. The apex of the arch is fairly high so that boats can also pass through easily. The bridge is ingeniously designed, with a well-proportioned layout, solid structure and a magnificent and attractive outward appearance. Willow branches sway gracefully at both ends of the bridge and, from afar, the inverted image of the arch in the water resembles a rainbow spanning over the Xiaohe River.

This is the oldest bridge in the world of its type, designed not of the usual arch bridges that marked previous dynasties, but more flattened, ideal for traversing troops and racing chariots. If the legend does not leave you impressed, the trials of history have more than vouched for the strength of this ancient structure. The bridge remains in good condition, with carefully supported stone structures beneath, and elegantly carved balusters, crowned with stone guardians, above, making this a highly valued piece for modern architects, engineers and lovers of art. The Chinese also like to mention another nearby bridge, the Forever Traversable Bridge (Yongtong qiao), that crosses the Qingshui River (Qingshui he). This is possibly only useful for those who are really interested in water crossings.