The Grand Old Duke of York
He had 10,000 men, d'you know? This is the Duke of York Monument off the Mall, with the Duke of York on the top; I've never known the viewing platform to be open, bit of a shame that - could be a candidate for Open House? He must have been popular with the soldiers, though, for all the futile marching, as they voted to donate a day's pay to construct this monument. Not the easiest thing to photograph, the rain helps.
Edit: Thanks to Hazeln for the pointer to Ian's story http://www.ianvisits.co.uk/blog/2012/10/30/closed-for-130-years-the-public-observation-tower-in-central-london/