The capitals in the colonnades of the central room of the Hagia Sophia in Istanbul are called `impost capitals with attached volutes'. They are important pieces of stone-mason's art in the sixth century a. C. The book presents a survey of capitals related to them - as complete as possible - , capitals from the same time, and interprets the shape of them and their variations. The resembling capitals show und explain the combination of their parts and make plain their ornamental particularities. - The church of San Marco in Venice possesses farther capitals of this kind, which were produced in the Middle Ages. They repeat the old models, but the differences are remarkable.