The National Gallery was the second-most visited attraction in the UK, with 6.03 million people coming through its doors (up 14% on 2012).
The Natural History Museum came in third place (up 6.7% to 5.35 million).
And several other London attractions also saw big increases, including Kew Gardens (up 29%) London Zoo (up 26.4%) the Tower of London (up 18.4%) and the National Maritime Museum at Greenwich (up 27%).
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The plaque at number 16 Cowley Street in Westminster marks the brown brick Georgian townhouse where Sir John lived for 31 years.
A man reportedly armed with several knives has been arrested in Whitehall on suspicion of planning a terror attack, police have said.
Metropolitan Police officer, Tom Harrison, has been crawling the course since the race began on Sunday morning.