Beijing’s metro network is the second largest subway network

on the planet. Shanghai is the largest. Beijing Metro is definitely one of the neatest and cleanest. More than 10 million people use the Metro daily and, on many days, I am one of them. The entire system has intelligent ventilation. When the train moves, you can feel the fresh air passing through the cars as if we were outdoors. 
The Beijing Metro is a very cheap, convenient, safe and fast way to travel within this megacity.