The Palace Museum in Beijing sold all its 80,000 tickets for the day online within two hours on Monday.

It is the first time for the Palace Museum, also known as the Forbidden City, to sell tickets online only, according to the museum.

Online advance sale of tickets initiated on September 25, 2011, when only 287 tickets were sold out. In August this year, 77 percent of tickets were booked online.

The museum plans to experiment with limiting the number of tickets for various periods of a day next year, based on big data analysis, so as to avoid overcrowding, said Shan Jixiang, curator of the museum.

The Palace Museum began to limit daily visitors to 80,000 in June 2015, preventing extreme peaks in number of visitors.

Every year since 2012, more than 15 million people have visited the museum. The number of visitors in 2016 hit 16 million.