View of an advertising card for Detroit Paving Block & Mineral Roofing Co., depicting men working in a factory. Printed on front: "Detroit Paving Block and Mineral Roofing Co. This company is now prepared to furnish a thoroughly tested and superior article for paving. Side walks, pleasure grounds, carriage drives, street crossings, cellar floors and warehouses. Also the best street paving block ever offered to the public. We also offer to builders a superior fire and waterproof slate, adapted to the covering of dwellings, depots, factories, saw mills, stables, etc. Office & factory, Atwater St., foot Jos. Campau Ave., Detroit, Mich." Printed on back: "Conger's patent paving blocks and mineral slates."