Complex sentence: In 1955, it was converted into the Shenyang Palace Museum and in 2004 it was included on the UNESCO World Heritage List in 2004 as an extension of the Imperial Palace of the Ming and Qing Dynasties in Beijing.
Split into simpler sentences: In 1955, it was converted into the Shenyang Palace Museum. In 2004, it was included on the UNESCO World Heritage List as an extension of the Imperial Palace of the Ming and Qing Dynasties in Beijing.