Furnace

View of the Furnace (praefurnium) where the fire burned to produce heat for the Hot Room (caldarium) of the Herod's Roman Bath at Masada. It is located outside of, and just to the east, of the bathhouse itself.

In the image note the stairs that lead down to where the wood was burned and the three openings that led to the under-the-floor area of the Hot Room—thus heating the floor above it.