In 2000, The Independent Newspaper named Ironmonger Row Baths as the 8th best in a rundown of the 50 best swimming pools in the world. Alright, this may be entirely subjective but it is a nice little pool, and it's fairly warm unlike some others in Central London.
The whole centre is run by Aquaterra for Islington Borough Council and is open daily. The Turkish Bath consists of a steam room, a series of three hot rooms of varying temperature, marble slabs for massage and body scrubbing and an ice-cold plunge pool.
It costs £3.90 for an adult swim and the Turkish Baths cost £13.30. The centre in Ironmonger Row is a short walk from Barbican or Old Street Tube Stations. You can read more at the Ironmonger Row Baths website at http://www.aquaterra.org/ironmonger-row-baths.aspx.