A flotilla of historic vessels, leisure cruisers and passenger boats pass under the Tower Bridge in a procession on the River Thames to mark the day on which Queen Elizabeth II becomes the longest reigning monarch in British history, in London, Britain, on Sept. 9, 2015. Wednesday marks the 63 years and 216 days since the Queen came to the throne. The procession began from east of Tower Bridge at midday, with the vessels sounding their horns for one minute. Also, the Tower Bridge lifted as a sign of respect. (Xinhua/Han Yan)
