Legendary stone structure withstands the test of time. Li Yang reports in Hebei province.

At the start of the Sui Dynasty (AD 581-618), when the country was unified after 300 years of chaos, the Zhaoxian county of Hebei province was a key route that linked the north and south. However the crossroad was often blocked by the Jiaohe River, especially during flood season. So the idea to build a bridge across the water was born. The Zhaozhou Bridge, locally nicknamed Dashiqiao, "big stone bridge", is built between AD 605 and 618, and is now one of the oldest and most renowned stone arch bridges in the world.

Architect Li Chun designed the bridge and led its construction. The large stone bridge, which was reinforced nine times and survived wars, floods and earthquakes during the past 1,400 years, still stands today.

The bridge is renowned for its endurance and longevity but also its combination of practicality and aesthetics, which include some of the oldest examples of delicate structures.

The 50.82-meter-long bridge has a 37.02-meter main arch and rises 7.23 meters above the river. The bridge is relatively flat, which made it easier for horse carts to roll across.

Two smaller arches on either side of the main arch add an element of visual symmetry. The design also lightens the overall weight of the bridge by 700 metric tons and enlarges its discharge capacity by about 16 percent. The four small arches also reduce the water's impact on the bridge when floods submerge the structure.