We had an _imperial architect_, with an unlimited amount of gold, silver, marble, wood, and precious material at his command, and yet he had to go back to the Greeks for elegant forms in ornamentation. He had Apollodorus executed for daring to find fault with the confused plan of the temple of Venus (_Amor_) _and Roma_, which was a building surpassing, so far as splendour went, any construction of those times. The double temple had certainly something whimsical in its plan. The Emperor was too forcibly struck by the discovery that _Roma_ read backwards gave _Amor_, and wanted to express this discovery in an architectural allegory, placing _two_ temples back to back so that they made _one_, to typify _two_ words with _two_ meanings, that yet were _one_ word. The success, so far as correctness of plan went, was doubtful. The cassettes of the bronze roof which united the _two_ temples into _one_, were most elegantly finished. The court of the temple was 500 feet by 300. Another tower-like circular monument, based on a square sub-structure, formed the Mausoleum (now the Castle of St. Angelo). The diameter of the circular part was 226 feet. The construction vies in solidity and grandeur with the Egyptian monuments. The blocks of travertin are colossal, and the immense building was covered with Parian marble, and crowned with a huge quadriga. Under the Antonines architecture, and art in general, gradually declined. The people occupied themselves with entirely different topics. Stoicism and Christianity--the old world of heathen formality, and the new world of spiritual redemption--were placed in conflict. A disturbed state of the public mind rarely favours plastic art. A specimen exhibiting this conflict may be seen in the temple of Antoninus and Faustina, built by Antoninus Pius (A.D. 138-161). A second edition of Trajan’s column is given in that of Marcus Aurelius (A.D. 161-180), which stands on the field of Mars. The reliefs, winding round the shaft, represent scenes from the war against the Markomanni. There is a certain liveliness in the execution, but the composition is wanting in clearness and precision, and above all in idealisation. Rivers, fields, and enclosures of walls, are marked with great accuracy; and the reliefs take, in style, the forms of geographical maps. Strict realism is the leading feature in this monument.