The oldest and strongest of the Greek columns belong to what is known as the Doric order (Fig. 9), a name given to them because they were first made by the Dorians, the original Greek dwellers in Europe. Aside from the flutes or channels which ran throughout its length the Doric column was perfectly plain. In the older Doric columns even the flutes are absent. Its _capital_ or top, was without ornament. Later the graceful and elegant Ionic pillar (Fig. 9) came into fashion. We can always distinguish an Ionic column by the volute or scroll at its capital. The latest of the Greek columns was the Corinthian (Fig. 9), the lightest, the most slender and the most richly decorated of all. A cluster of acanthus leaves at its capital is the most prominent ornament of the Corinthian column. The Greeks carried the art of column making to such perfection that even to this day we imitate their patterns. A column in a modern building is almost certain to be a Greek column. It is worth one's while, therefore, to be able to tell one Greek column from another. One can do this by remembering (1) that the Doric column is perfectly plain and has no capital; (2) that the Ionic column has a scroll at the capital; (3) that the capital of the Corinthian column is adorned with a cluster of acanthus leaves. [Illustration: FIG. 10.--AN OLD ROMAN ARCH.] Our story now takes us to Italy. Greece fell before the power of Rome 146 B.C., but before she fell she had taught her conquerors a great deal about architecture. Indeed the Romans took up the art of building where the Greeks left it. They needed the Greek gable for they had rains, and the Greek column recommended itself to them on account of its beauty. They used the best features of Grecian architecture and added a feature that was largely their own. This was the _arch_. The Greeks, like the Egyptians before them, bridged over the openings of doors and windows and the spaces between columns by means of straight wooden beams or long blocks of stone. The Romans bridged over these spaces with the arch (Fig. 10). If you will study the arch you will see that it is a curved structure which is supported by its own curve. You will also see that it is a structure of great strength. The greater the weight placed upon it, providing its bases are supported, the stronger it gets. In teaching the world how to make arches Rome added to the house an element of great strength and beauty. With the arch came the tall building. In Greece a house was never more than two stories high. In Rome arch rose upon arch (Fig. 11); the dome which is itself a kind of arch appeared and palaces were piled story upon story until they seemed to reach the skies.