This is just around the corner from where I work. it's right next to Oxford Street. The busiest shopping street in the UK.
A graffiti artist put up 3-story high scaffolding, painted this
painting, and took the scaffolding away again, without getting caught.
This is on a big wall in plain sight, on the grounds of a very busy Royal Mail sorting centre, which is fenced off, with CCTV cameras everywhere. Still nobody saw him, and it's not recorded on any camera.
Good job :)