Imperial Palace

The Imperial Palace in Peking was the main seat of Kublai Khan's empire. A banquet for an important guest might draw six thousand guests in attendance. In the summer, the Khan's court moved to his Summer Palace in Shang-Tu.

In the summer of 1289, the Khan prematurely moved his court from Shang-Tu to Peking when news came that Khan Noghai had encamped his army at Karakorum, six hundred miles from Shang-Tu. Peace talks were still to commence, but Noghai's emissary made an unsuccessful attempt on Kublai Khan's life as Noghai's army marched on Peking.

That same year, the Doctor's TARDIS was sent to the palace in Peking as a gift by Marco Polo, who hoped to bargain for his freedom to travel home to Venice. The First Doctor spent much of his time there playing backgammon with the Khan to win back his TARDIS. (TV: Marco Polo)

Part of the Imperial Palace later became a museum. One room of the museum holds a glass case with a TARDIS key on a gold chain known as "The Key to the World". (PROSE: Marco Polo)

Behind the scenes
Kublai Khan's Imperial Palace, was never converted into a museum, and it lies in ruins in the 21st century. In the story, it has likely been conflated with the later 15th century, which indeed does sit as a museum in modern times.