Ancient Roman Heating System From Furnaces
This page is the CodyCross answer for the clue below from Making a Documentary, Group 1520, Puzzle 2 (Audience Reception).
Question is: Ancient Roman Heating System From Furnaces
and the answer is: HYPOCAUST
Word Meaning:
HYPOCAUST — An underfloor space or flue through which heat from a furnace passes to heat the floor of a room or a bath.
Definitions from Wiktionary.