The Sproye Bridge (Guchai Bridge) was completed in 1408 as part of the city's defensive fortifications. Guchai Bridge is named because mills often pour chaff into rivers here. The last time almost all of them were destroyed in a fire was in 1993. Most noteworthy of all is the 67 triangular ancient paintings hanging in the corridor, which are simply open-air art museums. After the paintings were destroyed by the fire, several Swiss donated copies of their family's treasures to the restoration project.