reused in medieval Europe as well as in later periods. This reuse can be found across the former Roman Empire. In Great Britain, where construction materials are less plentiful, Roman structures were quarried for their stone and brick and it was commonly reused. Examples of this type of reuse in Great Britain can be found in Anglo-Saxon churches at Brixworth, Corbridge, St. Martin's, Canterbury, and St Nicholas', Leicester, and also in St Albans Abbey church (now St Albans Cathedral). Modern Modern "Roman" bricks were introduced at the beginning of the 20th century. They are invariably longer and flatter than other modern brick types, but there are no fixed dimensions. Those used in the United States in the early 20th century had nominal dimensions of : this gave them a 6:2:1 ratio, compared with a roughly 4:2:1 ratio of most modern brick types. Others with nominal dimensions of are also known. Demand has increased the availability of all types of bricks; there are more than a dozen commercially available brick types in modern construction. In 2011, the Roman Brick Company of Glasgow was offering "Roman" bricks in heights of 40, 52, 65 or 71mm; widths of 90 or 115mm; and lengths of 290, 365, 440, 490 and 600mm. Roman brick was introduced to the United States by the architectural firm McKim, Mead, and White. At one time, Roman brick was one of three available brick types in the United States; the other two were "Standard" and "Norman." By 1920, there were at least five types of bricks commonly available to builders and architects, among them: Roman, Norman, Standard, English and Split. Frank Lloyd Wright used Roman brick in his design for the Robie House in Chicago, and he favored it in many of his Prairie style homes. For the Robie House, Wright selected a brick later known as "Pennsylvania Iron Spot Roman brick", personally traveling to St. Louis to choose it. Wright's use of Roman brick in his masonry subtly emphasized the horizontal lines common to much of his Prairie style work. Further highlighting Wright's horizontal emphasis was the use of recessed horizontal mortar joints of contrasting color to the brick. The vertical joints were de-emphasized by ensuring the mortar was flush with, and of the same hue, as the brick. In modern times, as historic preservationists have worked to restore and preserve the work of Wright and his fellow Prairie