Connecting the eastern shore of Kunming Lake in the east and Nanhu Island in the west, the Seventeen-Arch Bridge was built during the reign of Emperor Qianlong (1711-1799); with a length of 150 meters (164 yards) and a width of 8 meters (8.75 yards). It is the longest bridge in the Summer Palace.

The unique scenery is but one of the stunning landscapes in the Summer Palace. With the styles of Lugou Bridge in Beijing and Baodai Bridge in Suzhou, Zhejiang Province, Seventeen Arch Bridge looks like a rainbow arching over the water. On the column of the parapets are 544 distinctive carved white marble lions. On each end of the bridge is a carved bizarre beast. With the biggest arch in the midst of the bridge flanked by sixteen others, visitors can count nine arches in different sizes from the middle to each end of the bridge. According to ancient thought, the number nine symbolizes good fortune and safety; and the meticulous design of the bridge embodies it perfectly.

There is an interesting legend connecting to the beauty of this bridge. It goes like this. One day during the construction of the bridge, an old man in shabby clothes came to the busy building site and shouted "Who wants Longmen (Dragon Gate) Stone?" He got no reply as the others took him as a crazy man on seeing his poor appearance. The poor man left with the stone in great disappointment. He stayed under a big tree, and every day, he chiseled the stone as early as when cocks started to crow. One night, it rained heavily, the poor man had to shelter from the rain under the tree when another elderly man saw him and asked him to live at his home. After a year went by, the old man said goodbye to the kind master and left the stone to him as a reward in return.

At the same time, the project of the Seventeen-Arch Bridge was almost finished except for a proper stone to fit the gap in the middle of the bridge. Someone advised the project director to find the man who once sold Longmen Stone. The director found out where the old man once lived. Out of extreme happiness, he found the right stone and gave the master some money to move it away. To everyone's excitement, the stone was exactly the right one to fit the gap. Suddenly someone realized, "The old man must be the incarnation of Luban (the earliest ancestor of carpenter) who came to help us to build the bridge!"