Complex sentence: The Round Pond in Kensington Gardens, London, in front of Kensington Palace, is not at all round, but more like a square with protuberances at the corners.
Split into simpler sentences: 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.