Keep an eye on the railings of London as you go about your business. 'Anonymous German street art collective' Mentalgassi have crafted these directional portraits onto various bits of ironmongery around the W1 area. Viewed head-on, the image is invisible; from the side, the likeness of a man becomes apparent.
That man is Troy Davis. He's been on death row since 1991 in the USA, despite serious doubts about his conviction. Amnesty International would like to see a retrial, and this clever use of street art - dubbed 'Making the Invisible Visible - is part of the awareness-raising campaign. Watch the video below for more details, and lend your support to the cause here.
The art installations can be seen at 4-7 Great Pulteney St, 21 Great Pulteney Street, and 5 Berners St.