When it rains, it pours. That was certainly the case in Beijing on July 20, when severe rainstorms hit the city, causing many roads and areas to become waterlogged. But the 600-year-old Forbidden City, remained free of flooding, thanks to its sound—albeit ancient—drainage system.

When images on social media popped up of the Palace Museum free of floods despite the heavy rainfall on July 20, it created a buzz on the internet.

Netizens were impressed by the ancient site’s drainage capabilities and compared its flood-free images with other photos and videos of the many flooded roads within Beijing after the tremendous downpour.

The 600-year-old Palace Museum, or the Forbidden City, remained free of flooding, thanks to its sound - albeit ancient - drainage system.

The ancient drainage system not only served its function, but also presented a rare scenario. Visitors of the Palace Museum that day were able to witness all 1,142 dragon spouts drain water from the upper platforms on which the principal palace halls were built.

“It is really an uncommon scene. Only when the rain is heavy can we see water pour out of these dragon drain spouts,” said Qi Fei, senior engineer, Palace Museum.

Built during the Ming Dynasty (1368-1644), the Forbidden City has been well-maintained over the past few centuries. Three types of drainage systems exist: One for the buildings, one for the surface runoffs, and one underground. Together they make up the entire system of the tourist site.

The altitude difference between the north gate and the south gate of the museum is almost 2 meters, and it created favorable conditions for a natural drainage.

The 600-year-old Palace Museum, or the Forbidden City, remained free of flooding, thanks to its sound - albeit ancient - drainage system.

According to museum curator Shan Jixiang, artifical drainage systems such as ditches, culverts and drain holes complete the network, which woks with modern systems to keep the palace safe from floods.

“The ancient drainage system in the Forbidden City symbolizes a spirit of craftsmanship that has been passed down for generations. However, the palace’s drainage and flood-prevention ability today is the result of many factors,” said Shan Jixiang, curator of Palace Museum.

The drainage system in the Palace Museum is a precious legacy left by the clever technicians and craftsmen of ancient times. The design has taken into consideration the weather, the soil and the people, all to reduce the peril caused by heavy rains.