Tens of thousands of pro-democracy demonstrators marching through the streets of Hong Kong as President Hu Jintao visits the former British colony to mark 15 years since its return to Chinese rule. June 1, 2012 (Photo/BBC)

DHARAMSHALA, June 1: Tens of thousands of pro-democracy marchers filled the streets of Hong Kong Sunday, as the former British colony marked 15 years since the return to Chinese rule.

The protests rallied around the swearing-in ceremony of Leung Chun-ying, a millionaire property consultant considered close to China's communist rulers, as the chief executive from Chinese President Hu Jintao.