Tower Bridge

Designed by Horace Jones and John Wolfe Barry, it opened in 1894 with Gothic-style towers so as to match the Tower of London. Its two bascules rise to let tall ships through, about 800 times a year, with hydraulics that ran on steam until 1976.

The paid exhibition takes you up to the high walkways, 42 metres up, with glass-floor sections to watch cars and boats pass beneath, and down to the Victorian engine rooms.