Task: Question Generation
Input (English): 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 in the 19th century 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.
Output (English): When was the Porcelain Tower destroyed?