While that one does look a lot like an old incinerator foundation, I have seen some old WPA wood ovens and pits that looked like that. It was not unusual to build them so that the draft from the chimney pulled air in over the coals.
"perhaps...but then again...maybe not..."
careful there son, those ribs are boiling hot...
(='.'=) Here there be bunnies...
Pacific Rim BBQ
Bob's Brew and Que