<human>:  When was the Kremlin built?
<bot>: The Kremlin was built in the late 15th century. It was originally built as a fortress for the Russian Tsar, Ivan the Terrible. In the 17th century, it was expanded and turned into a royal residence. In the late 19th century, the Kremlin was renovated and converted into a museum. It was added to the UNESCO World Heritage List in 1996.