Take the City of London. Grid it up into 100 squares. Give each one to a famous artist, designer or architect. Ask them to draw or paint a scene from that square.
The 100 participants include such luminaries as Lord Norman Foster, Ken Shuttleworth, and Sir Terry Farrell. Their collective efforts will today be auctioned off today by Sotherby's, with all proceeds going to Article 25.
Click through the gallery above for a selection of the drawings.