Ｔｈｅ Ｆｏｒｍｉｄａｂｌｅ Ｆｏｕｒ

Pollution， transportation， security and language are challenges that every Olympic host city must face. In the case of Beijing， matters are additionally problematic because this is a huge cosmopolitan city with more than 11 million permanent residents and a floating population of 4 million.