The Round Pond is a pond in Kensington Gardens, London, in front of Kensington Palace. It is, however, not at all round, but more like a square with protuberances at the corners. It is well known by this name to generations of local children who have used it to sail model boats (which sooner or later have to be retrieved by parents or keepers).
It was designed by Charles Bridgeman
More information on the Wikipedia page .