Chances are, if you have a cellar, that it's used for storage; wine perhaps, or no longer used toys. It's probably got a damp problem. Few of us are lucky enough to have one of these at the bottom of the stairs.
The current fashion for building downwards, so called iceberg houses (more below ground than above), has created huge creative opportunities for architects such as TP Bennett. The textured stone walls give the impression of the pool being dug from London's bedrock.
Alongside the pool and jacuzzi, are the mosaic tiled steam room, shower and WC.