Biggest in Europe
There is always something going on in London, even if you stay there for a month there will always be something new to discover.
Insider Tip:Buy the daily or weekly tube ticket (also works for the bus), and go for the free museums. There is a pass for many paid entries in the historical buildings, like the parliament, the westminster abbey and the tower of London, which is cheaper than paying individually. At night, Piccadilly Circus and Leicester Square are good options.