British Museum, Great Russell Street WC1

The great pediment over the front door of the British Museum was originally going to be unadorned as designed by Sir Robert Smirke in 1823, in accordance with the severe Grecian taste of the late Regency. By the time it was nearing completion in the 1840s, however, Queen Victoria was on the throne and people wanted things a bit richer, so Sir Richard Westmacott was brought in to egg the pudding.
The result is richly symbolic - the Progress of Civilization, no less. From left to right, an Unfortunate Pagan is brought the Light of Religion by an angel, and jolly grateful he is. Then come the embodiments of the arts and sciences, with Navigation, the Queen of Science, at the centre.
What I find fascinating is how Westmacott deals with the problem of the corners. He has to fill them in with something, so he inserts some of the animals that Captain Cook brought back from his voyages (they were a star part of the museum's collections before they were transferred to the Natural History Museum).
But to squeeze them into the pointy bits of the pediment he has to choose the animal kingdom's flattest creatures - a crocodile on the left and a turtle on the right.