Salisbury cathedral tower

Each tour spirals up 300 medieval stone steps to access the spire that defines Salisbury’s skyline and the fact it stands at all is a minor miracle. Built in the 14th century, the world’s tallest pre-1400 tower (123m) weighs 6,500 tonnes, causing the supporting pillars at the crossing to bow. Worse, the foundations are only 2m deep. Christopher Wren found it leaning nearly a meter off true, and like later architects, added the buttresses and iron ties that keep it standing today. Just as well, because it offers superb views over the town and countryside.