After making the walls of the base of the fireplace, I had to fill the great space in the middle. The kids and I hauled gravel and small rocks to the back of our property to do that job. After watering it overnight to make sure it was settled, I placed the firebrick (found at the local cement place!?). The actual fire-building area is 30" x 18". That little grill in there was found somewhere on our meadow and was placed there by one of my helpers. Eventually, I will have my dad (Dad?) build me a custom grill to fit the bricks. That way, we can use it as a charcoal grill during an emergency (or an adventure, whichever).