The Monument can lay claim to being London's first purpose-built viewing platform. It was erected in the 1670s by Christopher Wren as a reminder of the damage caused by the Great Fire of London.
It measures 203-feet from top to bottom -- the exact distance from its base to Pudding Lane, where the fire broke out. The 311 stone steps wind around the inner core until they open out into a wire-enclosed viewing platform at the top. The 360 degrees view takes in everything from the Gherkin and Tower Bridge, to HMS Belfast and St. Paul's Cathedral.
Coin operated telescopes at each corner allow you to look across the rooftops.
Note: Whilst the climb is not too strenuous, we do recommend (through experience!) that you are confident of your ability to climb a lot of steep stairs before you set out. They are no rooms on the way up, so the only way to rest is to sit on the stairs or the occasional window-sill.