Chislehurst Caves are a series of intersecting man-made tunnels and caverns covering some 22 miles (35.4 km) in Chislehurst in southeast London, England. From the mid-13th to early 19th centuries the 'caves' were created from the mining of flint and lime-burning chalk. During World War I the caves were used as an ammunition storage dump associated with the Royal Arsenal at Woolwich. In the 1930s the tunnels were used for mushroom cultivation.