Star-shaped anchor plates were used for structural reinforcement on buildings in the 18th and 19th centuries. These were made of cast iron and were used as tie plates serving as the washers for tie rods on brick or other masonry-based buildings. The tie-rod-and-plate assembly serves to brace the masonry wall against lateral bowing. Source - Wikipedia.
iPhone 5, 1/120 sec @ f/2.8, ISO 50, converted to black & white using Silver Efex Pro 2.