"They [the Romans] deemed that lightness and grace were to be attained not so much by proportion between the vertical and the horizontal as by the comparative slenderness of the former. Hence we see a poverty in Roman architecture in the midst of profuse ornament. The great error was a constant aim to lessen the diameter while they increased the elevation of the columns. Hence the massive simplicity and severe grandeur of the ancient Doric disappear in the Roman, the characteristics of the order being frittered down into a multiplicity of minute details." When the Romans used the Doric at all, they used a base for the column, which was never done at Athens. They also altered the Doric capital, which cannot be improved. Again, most of the Grecian Doric temples were peripteral,--surrounded with pillars on all the sides. But the Romans built with porticos on one front only, which had a greater projection than the Grecian. They generally were projected three columns, while the Greek portico had usually but a single row. Many of the Roman temples are circular, like the Pantheon, which has a portico of eight columns projected to the depth of three. Nor did the Romans construct hypaethral or uncovered temples with internal columns, like the Greeks. The Pantheon is an exception, since the dome has an open eye; and one great ornament of this beautiful structure is in the arrangement of internal columns placed in the front of niches, composed of antae, or pier-formed ends of walls, to carry an entablature round under an attic on which the cupola rests. The Romans also adopted coupled columns, broken and recessed entablatures, and pedestals, which are considered blemishes. They again paid more attention to the interior than to the exterior decoration of their palaces and baths,--as we may infer from the ruins of Hadrian's villa at Tivoli and the excavations of Pompeii.