Besides the city wall, other famous Ming-era structures in the city included the famous Ming Xiaoling Mausoleum and Porcelain Tower, although the latter was destroyed by the Taipings <answer>in the 19th century</answer> either in order to prevent a hostile faction from using it to observe and shell the city or from superstitious fear of its geomantic properties.
When was the Porcelain Tower destroyed?
in the 19th century