The Berkeley

The Berkeley's headline act is its rooftop pool — seven floors up, with a retractable roof so you can swim under London sky in summer and steam through the grey in winter. The sauna and steam room round out one of the more genuinely pleasurable spa floors in Knightsbridge. The hotel itself is a Maybourne property, which means service is impeccable and the design is forever being quietly refreshed by big-name names. It manages the trick of feeling grand and slightly playful at once. For a heat session that ends with a swim above the rooftops, it's a hard one to beat, and it's a touch warmer in feel than some of its more formal neighbours. Pool and sauna access is included for guests; the rooftop is popular, so go early or late.