How is a 65 year old concrete landmark repaired and restored to its original strength and finish? Unity Temple, declared a Registered National Historic Landmark building in 1971 by the National Park Service, provided a unique challenge for architects and contractors responsible for the repair and resurfacing of the structure using a pneumatically applied pea gravel concrete coatings. A shotcrete coating was chosen as the best way to restore the original finish. To ensure a good mechanical bond to the original concrete wall the architects required the contractor to deeply etch the cement coating applied in 1961 and expose the original pea gravel aggregate. He achieved this with a heavy abrasive blast using power house slag blasting grit. Pea gravel similar to that in the original mix was located in Algonquin, Illinois, in the Fox River Valley. Type I portland cement and Number 2 torpedo sand were used. The new coating was pneumatically applied in a thickness not exceeding three-fourths of an inch. Much of the coating is less than one-half inches thick. It was finished with trowels and then abrasive blasted with slag to expose the aggregate. The finished surface is protected with the equivalent of two coats of boiled linseed oil, the first cut 50 percent with mineral spirits and second full strength.