According to that great compendium of knowledge, Wikipedia, a fisheye is "an ultra wide-angle lens that produces strong visual distortion intended to create a wide panoramic or hemispherical image."
Used subtly, the fisheye can bring a whole new perspective to familiar sights, as this selection of London landmarks demonstrates. The interiors of our great buildings — the Natural History (our favourite here!) and British museums, the Foreign Office — appear even more grand and cavernous. London underground's concave tunnels, meanwhile, become futuristic and claustrophobic given the fisheye treatment.
Finally, looking upwards brings a new look with this bit of photographical trickery too. The London Eye looks completely different while St Paul's becomes uncomfortably sandwiched between two brick slabs. Lots of fun all round.
With thanks to Londonist Flicker pool contributors: FJC37, James Guppy, Londonietis, becksflrt, Romany WG and *junket*.