There is a certain apophatic quality to The World of Stonehenge at the British Museum, which is defined by the absence at its centre—not unlike a Polo, the mint with the hole. This applies figuratively, in the sense that what anyone actually knows about Stonehenge is still very limited, and literally in the case of the stones themselves, which remain safely on their picturesque traffic island in Wiltshire. This is a poser, obviously, for any curator: how to lay on an exhibition about something that isn’t there, created by a culture that left no written records.