Many years ago, as tourists in Havana, we were shown the Cuban "kilometre zero" - the point from which all distances to and from Havana are measured. I remember being treated as an idiot when I asked how you would know where the other end of the line would be. Maggie added her scorn to that of the guide.
True enough you can measure to a point form any other point but where do you measure from? The roadsigns say, for instance, 70 miles to London but to where in London? - Westminster Abbey maybe - and if so the door or the altar - or it could be Buckingham Palace or, perhaps, The House of Commons. Apparently, in London, it's to the statue of King Charles I on the South side of Trafalgar Square.
In Madrid it's very obvious. Tourists queue to have their pictures taken standing on or near the Km0 point in the Puerta del Sol. And, yesterday, in Murcia I was shown the point to which all distances to and from Murcia are measured.
So, Cuban tourist guide, I can work out how far it is from London, Murcia or Madrid to Havana but can you tell me how far it is to Culebrón from Havana if you're so smart?