Roman Style Heater

Making living easier was always their priority. So, the Roman engineers applied a quite effective method to keep the house warm during winters. As it was hard to keep a furnace burning for  24*7 inside home, they invented another method to circulate hot air throughout the building by using hollow spaces in the columns. The furnace was kept under below the floor and the hot air reached to every corner of the house through hollow places. A smart technique, right?