The running time of Beijing 2003 is 150 hours (more than 6 days) which makes it the third longest movie in the world. As you figured out, it was a Chinese movie by Ai Weiwei released in 2004. This is a part of documentary series about social and political activism. Apparently, it was an allusion because the whole movie is some sort of a long ride in the car through Beijing. The directors made their way through every street of Peking's ring road – that's 1,491 miles (about 2,400 km). The camera captures objectively the streets and the people of Beijing giving us the opportunity to make our own conclusions.
2nd place in "Top Ten Longest Movies In History"
Beijing 2003 is the third longest movie in the world. It's running time is more than 6 days. It was a part of documentary series