Beijing's subway Line 4 runs from north to south, passing through many important and interesting places, including the Summer Palace, Peking University, Zhongguancun, the National Library of China and the Beijing Zoo.

Entering the Beijing Zoo station, passengers cannot avoid being immediately attracted to a colorful mosaic wall painting. The painting is full of cartoon-style animals such as grey rhinoceroses, red horses and black and white pandas.

Commuter Yan Nan says she likes the artwork very much.

"I am impressed by its polychrome colors. It is very visually striking. I also like the wall sculpture in the Summer Palace station. Looking at it is like reading a book. It reminds me of that historical period. These art decorations make my trip interesting."

The pillars in the Summer Palace subway station have been made to look like the palace's own destroyed pillars.

In the Xidan station, passengers can see reliefs featuring traditional Beijing folk acrobatics and performances.

In an effort to bring classic art into the mass transit network, two of the trains that run on Line 4 have turned 10 carriages into art galleries.

Here is Wu Huaiyi, Director of the mobile art galleries.

"The galleries and Line 4 opened simultaneously. Every 45 days, we change our exhibits. The first exhibition features oil paintings by famous Chinese artists. The second one features water-and-ink paintings by modern Chinese female artists."

Wu Huaiyi says all the artists have provided their works free of charge. In the future the mobile art galleries will include photographs, paper-cuttings and sculptures as well as the works of foreign artists.

Not all the art works have caught attention of passengers. Two contemporary sculptures sit in the National Library station. But some commuters like Yan Nan seem not to be interested in them at all.

"They are too small to be noticed. What's worse is that they are placed behind the big pillars. Wall decorations are more suitable for crowed and busy places like the subway. They don't get in the passengers' way like sculptures."

Now almost every place in the subway stations can be turned into advertisement space to make money.

But Wu Huaiyi says Beijing's use of art in public places is just starting to develop, so that the government and the subway operators need to find a balance between public welfare needs and profits.

Some professionals suggest that every public venue and building should dedicate 1 percent of its construction funding on artistic design and decoration.