This is one of the altars to the Four Elements.  The central shape was inspired by one of Frank Lloyd Wright's broad, multi-layered arches.  The overhead vault is clad in mirror to reflect light and heat into the living room. The side portals are for wood storage, each having doors to the outside,  thus minimizing work and mess.  The firebox is a Rumford design, shallow and tall to throw more of the heat into the room.  The hearth is at living room floor height to take the fullest advantage of the rising heat, but reached via a sunken pit 2 steps down.  This smart little design trick not only keeps you from having to bend over, but also contains the inevitable mess, flying sparks, etc., that plague the owner of a standard hearth.  Another added plus is the working drain in the center for hose-downs.