The only place in Britain where you can bathe in naturally hot spring water. The modern glass-and-stone building, designed by Nicholas Grimshaw, sits over the same thermal springs the Romans used two thousand years ago. The highlight is the open-air rooftop pool, where you float in warm mineral water with views over the Bath skyline and the surrounding hills — particularly atmospheric at dusk or on a cold winter evening when steam rises around you.
Inside there are two further pools, steam rooms infused with different essential oils, and a series of treatment rooms. A standard session of two hours costs around thirty-five pounds, which is enough time to enjoy the pools and steam rooms without rushing. Weekday mornings are quietest. Towels and robes are available to hire. The separate Cross Bath next door, a smaller and more intimate open-air pool in a historic shell, can be booked for private sessions.