Creeping around the breakwater that protects Fort Wool's wharf, it's difficult not to be struck by the fort's most awkward edifice: Its observation tower. Added during the brief enthusiasm for coastal defense at the beginning of the Second World War, it seems both un-aerodynamic and a particularly tempting target for the deck guns of German U-Boats. But it's still standing, so perhaps its designers knew something I don't, unlikely though that might seem.