London is a popular centre for tourism, one of its prime industries, employing the equivalent of 350,000 full-time workers in 2003,[229] while annual expenditure by tourists is around £15 billion.[230] London attracts over 16 million international visitors per year, making it Europe's most visited city.[231] London attracts 27 million overnight-stay visitors every year.[232] In 2010 the ten most-visited attractions in London were:[233]