While there are those who would argue that reinforced concrete could have no possible place in the exposed areas of a cathedral that dates back to the 12th century, nevertheless this modern material has been used with good effect in the restoration of Llandaff Cathedral in England. The new work in this medium has achieved complete esthetic harmony with eight centuries of craftsmanship, while at the same time it has carried on the tradition which has permitted each period to place its own stamp upon the total structure. Although no deliberate effort was put forth to make the concrete of the arch to resemble stone, it was considered of the utmost importance that in color and texture it should harmonize with the limestone that predominates throughout the structure. To accomplish this the Cement and Concrete Association devised a special mix with the following proportions by volume: 1 part white portland cement plus 5 percent by weight of khaki Colorcrete; 1 and one-half parts Derbyshire spar, grade B, minus one-tenth inch; 3 parts portland stone passing three-eighths of an inch and retained on a three-sixteenths of an inch sieve. The arch was first hand tooled and the outer skin of concrete removed. Since it was though that the resulting texture was somewhat coarse, mechanical tooling was eventually undertaken to obtain a finer grained finish.