The Romans had an elaborate system
of hot and cold pools, saunas
and spa treatment rooms at the Baths.
Hot rooms and saunas were heated by
an ingenious central heating system, called a Hypocaust.
Above are the columns which once supported
the floor of a steam-room.
Furnaces lit at the sides of the underfloor
system allowed the heat to circulate between the columns
and heat the room above.