Xanadu, also Zanadu, Shangdu or Shang-tu (Chinese: 上都; Hanyu Pinyin: Shàngdū) was the summer capital of Kublai Khan's Mongol Empire, which covered much of Asia and also encroached upon eastern Europe. The city was located in what is now called Inner Mongolia, 275 km north of Beijing, about 28 km northwest of the modern town of Duolun. The capital consisted of the square-shaped "Outer City" (2,200 metres square), "Inner City" (1,400 metres square), and the palace, where Kublai Khan stayed in summer. The palace was 550 metres square, 40% the size of the Forbidden City in Beijing. The most visible modern-day remnants are the earthen walls though there is also a (ground-level) circular brick platform in the centre of the inner enclosure. Xanadu was visited by Venetian explorer Marco Polo in 1275; it became fabled as a metaphor for opulence.

The Mongol Emperors of the Yuan Dynasty made very few changes to China, imbibing much of the Confucianist and Taoist philosophies, and remodelling their government on the native dynasties they had defeated. However, they opened up the empire to westerners, allowing travellers like Venetian explorer Marco Polo in 1275 to report the wonders of the Eastern capital to their fellow Europeans.

The reported splendour of Xanadu later inspired Samuel Taylor Coleridge to write his great poem Kubla Khan and caused Xanadu to become a metaphor for opulence. Xanadu is remembered today largely thanks to this poem, which contains the following often quoted lines: : A stately pleasure-dome decree: : Through caverns measureless to man : So twice five miles of fertile ground : And there were gardens bright with sinuous rills, : And here were forests ancient as the hills, Coleridge used artistic license with his poem, and few aspects of the description are in evidence at the actual site. The author claimed that his composition was suggested by a line in Purchas His Pilgrimage.

Xanadu is a song recorded by the Canadian progressive rock trio Rush for their 1977 album A Farewell to Kings. It is approximately eleven minutes long, beginning with a five-minute-long instrumental section, then transitioning to a narrative written by lyricist Neil Peart, inspired by the Samuel Taylor Coleridge poem Kubla Khan.

"Xanadu" is the title song from the album Xanadu, the soundtrack to the 1980 film of the same name. The song is performed by the Electric Light Orchestra (ELO) with vocals by Olivia Newton-John.

A rare collaboration for ELO, it is the band's only UK #1 single for two weeks in July 1980. The song peaked at #8 on the Billboard Hot 100 in the US.

In 2000, ELO's Jeff Lynne re-recorded the song with his own vocals for the box set Flashback and the All Over The World compilation.

The song is being performed as part of the 2007 Broadway musical Xanadu.

This song appeared in the 4th episode of Season 4 of the TV show Lost, Eggtown.