Rama I's grandson, King Rama III (1787–1851), decided to build a chedi of huge dimensions inside Wat Saket. Unfortunately, the chedi collapsed during construction because the soft soil of Bangkok could not support the weight. Over the next few decades, the abandoned mud-and-brick structure acquired the shape of a natural hill and was overgrown with weeds. The locals called it the "phu khao" (ภูเขา), as if it were a natural feature.