Among the less pleasing peculiarities of the Persian architecture may be mentioned a general narrowness of doors in proportion to their height, a want of passages, a thickness of walls, which is architecturally clumsy, but which would have had certain advantages in such a climate, an inclination to place the doors of rooms near one corner, an allowance of two entrances into a great hall from under a single portico, a peculiar position of propylaea, and the very large employment of pillars in the interior of buildings.  In many of these points, and also in the architectural use which was made of sculpture, the style of building resembled, to some extent, that of Assyria; the propylaea, however, were less Assyrian than Egyptian; while in the main and best features of the architecture, it was (so far as we can tell) original.  The solid and handsome stone platforms, the noble staircases, and the profusion of light and elegant stone columns, which formed the true glory of the architecture—­being the features on which its effect chiefly depended—­have nowhere been discovered in Assyria; and all the evidence is against their existence.  The Arians found in Mesopotamia an architecture of which the pillar was scarcely an element at all—­which was fragile and unenduring—­and which depended for its effect on a lavish display of partially colored sculpture and more richly tinted enamelled brick.  Instead of imitating this, they elaborated for themselves, from the wooden buildings of their own mountain homes, a style almost exactly the reverse of that with which their victories had brought them into contact.  Adopting, of main features, nothing but the platform, they imparted even to this a new character, by substituting in its construction the best for the worst of materials, and by further giving to these stone structures a massive solidity, from the employment of huge, blocks, which made them stand in the strongest possible contrast to the frail and perishable mounds of Babylonia and Assyria.  Having secured in this way a firm and enduring basis, they proceeded to erect upon it buildings where the perpendicular line was primary and the horizontal secondary—­buildings of almost, the same solid and massive character as the platform itself—­forests of light but strong columns, supporting a wide-spreading roof, sometimes open to the air, sometimes enclosed by walls, according as they were designed for summer or winter use, or for greater or less privacy.  To edifices of this character elaborate ornamentation was unnecessary; for the beauty of the column is such that nothing more is needed to set off a building.  Sculpture would thus be dispensed with, or reserved for mere occasional use, and employed not so much on the palace itself as on its outer approaches; while brick enamelling could well be rejected altogether, as too poor and fragile a decoration for buildings of such strength and solidity.