Why the Marble Arch Mound is a slippery slope to nowhere

The artificial hill in central London seems a great idea, but it would be better to have done something that genuinely helped the environmentThe Torre Guinigi in Lucca, Italy, is a brick medieval tower – it’s handsome, but of a type common enough in historic Tuscan cities. What makes it special is a grove of holm oaks growing from its summit. Trees come with expectations, such that they are rooted in the ground, yet there they are, high in the air, apparently flourishing. The tower w