The material used at Hatra is uniformly a brownish gray limestone; and the cutting is so clean and smooth that it is doubted whether the stones have needed any cement. If cement has been employed, at any rate it cannot now be seen, the stones everywhere appearing to touch one another.
There are several buildings remaining in Persia, the date of which cannot be much later than that of the Hatra edifice; but, as it is on the whole more probable that they belong to the Sassanian than to the Parthian period, no account of them will be given here. It will be sufficient to observe that their architecture grows naturally out of that which was in use at Hatra, and that thus we are entitled to ascribe to Parthian times and to subjects of the Parthian Empire that impulse to Oriental architecture which awoke it to renewed life after a sleep of ages, and which in a short time produced such imposing results as the Takht-i-Khuzroo at Ctesiphon, the ruins of Shapur, and the triumphal arch at Takht-i-Bostan.
The decorative and fictile art of the Parthians has received no inconsiderable amount of illustration from remains discovered, in the years 1850-1852, in Babylonia. In combination with a series of Parthian coins were found by Mr. Loftus, on the site of the ancient Erech (now Warka), a number of objects in clay, plaster, and metal, enabling us to form a fair idea of the mode in which purely Parthian edifices were decorated during the best times of the empire, and of the style that then prevailed in respect of personal ornaments, domestic utensils, and other objects capable, more or less, of aesthetic handling. The remains discovered comprised numerous architectural fragments in plaster and brick; a large number of ornamental coffins; several statuettes in terra-cotta; jars, jugs, vases, and lamps in earthenware; some small glass bottles; and various personal decorations, such as beads, rings, and earrings.
The architectural fragments consisted of capitals of pillars [PLATE V. Fig. 3], portions of cornices, and specimens of a sort of diapering which seems to have been applied to screens or thin partitions. The capitals were somewhat heavy in design, and at first sight struck the spectator as barbarous; but they exhibited a good deal of ingenious boldness, an absence of conventionality, and an occasional quaintness of design not unworthy of a Gothic decorator. One especially, which combines the upper portion of a human figure, wearing the puffed-out hair or wig, which the Parthians affected, with an elegant leaf rising from the neck of the capital, and curving gracefully under the abacus, has decided merit, and is "suggestive of the later Byzantine style." The cornices occasionally reminded the discoverer of the remarkable frieze at El-Hadhr, and were characterized by the same freedom and boldness of invention as the capitals. But the most curious remains were the fragments of a sort of screen work, pieces of plaster covered with geometric designs upon both sides, the patterns on the two sides differing. [PLATE V. Fig. 4.] These designs, though unlike in many respects the arabesques of the Mohammedans, yet seemed on the whole to be their precursors, the "geometric curves and tracery" appearing to "shadow forth the beauty and richness of a style which afterwards followed the tide of Mohammedan conquest to the remotest corners of the known world."