What is it?

I'm tired so I can't be bothered to think a lot. 21.2 miles up to Dobbs Weir along the River Lea first this morning has left me in pieces so I haven't got the intelligence to take a photo is something interesting. Kind of understandably North London gets a bit of a bad press but the sights, sounds and peacefulness of the Lea going North is very very pleasant. I want a house backing onto the river in Broxbourne.

Anyway don't distract me... What is this image of? The prize if you get it correct? My sweaty running kit...