Some of the museums which have been added are the Beijing Soap Museum and the China Bee Museum, but some others, like the China National Film Museum, have temporarily quit the program due to renovation.

The annual pass in 2018 included 113 institutions.

Cao has endeavored to produce an annual pass for 15 years. His team also provides a series of auxiliary services.

Cao says: "When people visit museums regularly, they become thirsty for knowledge. So, they will not be satisfied with just a random walk in an exhibition hall."

As a result, Cao has organized more than 100 free lectures for the public since 2016.

The talks focus on traditional Chinese culture and ancient civilizations.

He also leads group tours to historical sites nationwide to echo the current exhibitions taking place in the museums.

He says: "For each lecture, we used to have only a 100-person capacity, so they sometimes sold out within three minutes. People's interest in museums has grown rapidly."

Some frequent attendees of these activities have since become volunteers to promote the museums.

One of them is Zhou Ya.

Speaking about the pass, Zhou says: "It is not only a book of tickets. It is a gateway to a different lifestyle."

She says it could also change the global image of Chinese tourists abroad.

"They (Chinese tourists abroad) are often unfairly labeled as people who just go shopping," she says.

"More visits to museums (at home) will help us nurture a cultural consciousness and make us naturally want to go and see local art when we go overseas."