Two architectural merits have been pointed out in the Coliseum, the impression of height and size conveyed by the tiers of arches rising one above another, and the graceful curves produced by the continuous lines of the entablatures as they cross the building. But what the Roman emperor under whose auspices this great building was raised would doubtless have valued more than any elegancies of design which could have been pointed out to him, is the perfect adaptation of the structure to its purposes. After the great catastrophe at Fidenæ where 20,000 persons were injured or killed by the breaking down of a wooden amphitheatre, solidity and safety were the principal requisites. Free ingress and egress for crowds of spectators, as well as for any great personages who might attend, was indispensable. A glance at the plan of the Coliseum will show how admirably each of these objects was attained. The extraordinary solidity of the building removed all possibility of the failure of any part to bear whatever weight might be heaped upon it, and the entrances, galleries and vomitoria were by the oval form of the building rendered so numerous that each seat in the whole cavea was accessible at once and without difficulty. A system of carefully arranged barriers in the passages would effectually prevent confusion and excessive crowding. In endeavouring to adorn the great amphitheatre of the metropolis more richly than those of the provinces its architect defeated his own object. Some of the provincial amphitheatres, as that of Capua, though in other respects like the Coliseum, show a simpler and therefore more natural exterior. When the Doric order is retained in all the tiers, it harmonises far better with the rude strength of such an edifice than the Corinthian and Ionic orders of the Coliseum. At Verona and Pola a still further improvement is made by the rustication of the exterior. At Nismes, on the other hand, the faults of the Coliseum are aggravated by breaking the entablatures, and introducing pediments over each front; and in the small Amphitheatrum Castrense at Rome, where the Corinthian order is executed in brick, a lamentable illustration of Roman want of taste is exhibited. [Illustration: MONS OPPIUS. After Palladio and Canina.]