Free and inexpensive things to see and do in London

All over central London there are racks of blue bikes for rent; they’re known as “Boris bikes” after the cycle-crazy mayor who introduced them in 2010. You need to insert your credit card at the docking station and pay £1, about $1.55, for access. After that, the first half-hour is free.   (Justin Tallis / AFP/Getty Images)

Some of London’s greatest pleasures and bargains are its free museums, but not everyone knows that once a week they are open late. It’s a lovely time to see your favorite pictures without the crowds and school groups. The National Gallery is open until 9 p.m. Fridays when it has free music and a wine bar.   (Dan Kitwood / Getty Images)

In the East End of London, the Columbia Road flower market opens every Sunday, rain or shine. Rachel Bramwell, who grew up in Silver Lake, Los Angeles, before coming to London for grad school and work, clutches a fresh purchase.  (Christopher Reynolds / Los Angeles Times)

Riding on top of a red London bus is fun wherever you want to go. Buy an Oyster card bus pass to get the cheapest fares; otherwise, the standard bus fare is $3.45.   (Peter Macdiarmid / Getty Images)

The quintessential free London experience. Two morning changings: one by the Horse Guards on Whitehall and one at Buckingham Palace. The one at the palace is bigger and has a marching band. Arrive at least half an hour early. For the palace changing, stand so you can see across to Birdcage Walk, where the new guard marches up in scarlet tunics, rather than pressing against the palace railings.   (Marco Simoni / Getty Images)