This detail of architect Fitzroy Doll's cross-section through the Turkish baths at London's Imperial Hotel shows, in the centre, below the sub-basement, the plunge pool which passed beneath a decorated glass screen allowing bathers to pass from frigidarium to tepidarium, or vice versa.

These two rooms, both two storeys high, occupied the sub-basement and basement of the 1913 extension to the hotel. Immediately on either side of this 'nave' were two aisles, in the upper part of which were the cubicles for changing, furnished with couches for relaxing on after the bath.