Dan Cruickshank’s Bridges: Heroic Designs that Changed the World. Dan Cruickshank

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      Detail of one of the arched and open spandrels of the Zhaozhou or Anji Bridge. This is the world’s oldest surviving open-spandrel, segmental arched bridge built in stone. The joints between the masonry blocks forming the arches are reinforced by wrought-iron bars or cramps.

      For all these reasons bridges have been applauded as heroic, sacred – almost mystic – works by all cultures. Bridges of great scale or span were venerated in Medieval Europe, either as pious works that glorified God or as almost impossible acts of daring that could only have been achieved with the aid of the Devil (see page 94). Great bridges were, people assumed, creations that could only be completed through prayer and divine guidance or by the sale of the soul to dark forces. They were places where you could meet angels and saints as if conducting you to Heaven, or the Devil himself collecting his toll. Similarly in China: the truly remarkable Zhaozhou or Anji Bridge in Hebei province, built between 595 and 605 AD to the designs of Li Chun and the world’s oldest open-spandrel segmental arched masonry bridge, is particularly rich in myth, legend and stories of the supernatural. This is mainly because its construction methods and ambitious scale – its main arch of segmental forms spans a mighty 37.7 metres – astonished most contemporary observers. Li Chun achieved the wide span of the bridge by using 28 parallel and abutting arches, each formed with massive, precisely cut and wedged limestone voussoirs whose joints were strengthened with wrought-iron cramps or bars. The arch-topped open spandrels not only reduce the weight of the bridge without weakening it but also – by creating additional openings through its body – protect the bridge from being washed away by the force of unusually high and powerful flood waters. These novel design features and construction techniques gave the bridge great strength but also the flexibility necessary to withstand earthquakes.¹

      Li Chun – clearly a man of advanced practical know-how – was himself not ignorant of the worlds of magic and of the spirits. The bridge is of pure, simple and practical design yet the keystones at the crown of the main arch are embellished with carvings that show the leering and horned heads of the Taotie motif. These beings from the spirit world were intended to protect the bridge from floods and from the potentially malevolent spirits of the river that might resent the bridge, for it robbed them of some of their power over those mortals who wanted to cross the water. In a Taoist culture, where all is animated and nature is seen as the great guide and inspiration, everything is alive – not just the river but the stones from which the bridge is made and, indeed, the bridge itself.

      One legend about the bridge is like those attached to many European medieval bridges of prodigious span or slender form: it was constructed by an inspired human, in this case the fifth century BC engineer and philosopher Lu Ban, working with the aid of spirits. Another legend is that two Taoist Immortals – perfected beings who are masters of time and space and travel between the earth and the distant stars – decided to test the strength of this unprecedented bridge by thundering across it in tandem. The bridge survived this ordeal just as it survived resentful water spirits and – perhaps more impressively – earthquakes and centuries of neglect. It still stands, still does the job for which it was built 1,400 years ago, and continues to inspire and astonish – a thing of perpetual delight and timeless beauty that contrives, despite all it has seen and suffered, to look eternally youthful and modern.