I was at bank station on my way out from the centre of London, when I came upon this scene. The central line and northern line platforms are currently undergoing some construction and upgrade work. This is the the portion of the platform tunnel where advertisements (left and right) are usually placed with the TFL Roundel in the centre between them. During construction, the advertising boarding and TFL Roundel was temporarily removed, revealing the impressions left after years of grime and the hot moist air. The chaos, destruction, water damage, mould and colours created this stunning effect.