June 29 marked a historic day for the Site of Xanadu in the Inner Mongolia autonomous region and Chengjiang Fossil Site in Southwest China's Yunnan province, as they gained places on the World Heritage List.

That announcement came at the 36th session of the UNESCO's World Heritage Committee in Saint Petersburg, Russia.

Tourists visit a site of Xanadu in the Inner Mongolia autonomous region last year, which was added to the World Heritage List on Friday.

China's only candidate for World Cultural Heritage status this year is the first to be in Inner Mongolia, as well as the country's 42nd World Heritage site and 30th World Cultural Heritage site.

"Xanadu is the best-preserved among the Yuan Dynasty's capital cities and has lasted the longest," said Tong Mingkang, deputy director of State Administration of Cultural Heritage.

"It's the only intact evidence of the rise and fall of the Yuan Dynasty (1271-1368), which witnessed the unique fusion of agrarian Han Chinese and nomadic Mongolian civilizations in northern Asia."

Lying in Zhenglan Banner and Duolun county of the Xilin Gol League in central Inner Mongolia, Xanadu was the first capital of Kublai Khan (1215-94) and later became the summer capital of the Yuan Dynasty.

Six of 11 Yuan emperors ascended to the throne in Xanadu. But the city was destroyed in fires over the course of a decade starting in 1358 and eventually abandoned.

Shaped like a square, Xanadu has a central axis marked by an imperial city and a palace city, which is surrounded by an outer city. When the Yuan Dynasty moved its capital to Beijing, it built the Forbidden City in a position that aligned it with Xanadu's axis.

Archaeological explorations have uncovered the underground remains of the old capital, which had been covered by grasslands. Since 2008, archaeologists have confirmed the discovery of 1,078 building sites, 700 construction foundations and 29 large streets.

"Some of the city's attributes, such as its water drainage system, were already quite advanced compared with what we have today," said Tala, curator of the Inner Mongolia Museum and director of the Xanadu archaeology team.

Some of the cultural relics - for example, white marble columns bearing dragon designs and three-color glazed roof tiles - were evidence of the high aesthetic standards that were observed at the time, Tala said.

Archaeologists have also found Christian churches, mosques and Buddhist temples beneath the grassland. The tombs of Europeans have meanwhile been discovered in Zhenzi Mountain in Duolun county.

"Xanadu had a profound and long-lasting influence on relations between the East and West, and has inspired literary and other creative works throughout the centuries," Tong said.

The Venetian traveler Marco Polo (1254-1324) is believed to have come to China around 1275 and to have gained an audience with Kublai Khan in the palace of Xanadu. When he returned home years later, the tale of his adventures was told in what became the book The Travels of Marco Polo.