Shangri-La The Shard, London

There's no other sauna in London quite like sweating 52 floors above the city, with the Thames unspooling below and the whole skyline laid out through the glass. The Shangri-La occupies the upper reaches of the Shard, and its wellness floor — sauna, steam, and that much-photographed infinity-edge pool — makes the most of the altitude. It's a genuine wow, and worth timing for sunset. The hotel itself is sleek and pan-Asian in feel, with floor-to-ceiling windows in every room that turn the view into the main event. It leans more modern-glamorous than cosy, and the pool gets busy, but for sheer spectacle the heat-with-a-view experience is unbeatable. Sauna and pool access is included for guests; go early in the day if you want the view mostly to yourself.