When I removed a cabinet from our basement wall today I discovered the panel in the photo below. The panel is metal, approximately 2 ft wide and 1 ft high. It has five 1.5 inch holes in it, each one covered in mesh (see close up). Behind the mesh I can see gravel. This plate is located in the basement wall directly below the front door. The plate is approximately 4 ft from the basement floor, and 2 ft below ground level (i.e 2 ft below the front door). The house has a cinder block foundation (but there is no cinder block behind the panel). The house was built in 1949. There are no utilities entering the house near the panel. Any ideas what it could be for? Many thanks! 
Best Answer
Would this be in an area that snows or could get cold. It's not a coal chute as most of those were not under the front door. My thinking is this - Warmer air from the cellar escapes and keeps the area in front of the door free from ice and snow -hence the gravel which probably extends down the outside wall. Its a simple convection heat source and very energy efficient.