| Among the most solidly preserved of all Roman | | | | upper storey do not continue the vertical lines of the |
| architectural inventions are the monumental arches, | | | | pilasters which flanked the archway below, which |
| buildings of a type devised purely for display. This | | | | were taken up by the statuary which stood in the |
| conversion to monumental form of the temporary | | | | openings of the upper storey. Some second-century |
| structures created for the occasion of military triumphs | | | | and later arches and gates were highly elaborate, with |
| in Rome is yet another instance of rapid evolution in | | | | a façade architecture of niched figures framed |
| Augustan architecture. The main arch passage, and | | | | by luxuriantly decorated pilasters, as on the Porte Noir |
| any side passages, as on Trajan's Arch at Timgad | | | | at Besançon and the London Arch. In contrast, |
| and that of Septimius Severus in Rome, was flanked | | | | the Porta Nigra at Trier, with quadruple tiers of |
| by columns, usually in pairs. The intervening spaces | | | | regularly-spaced columns framing arched openings, is |
| might contain aediculae or relief sculpture relevant to | | | | reminiscent of the exteriors of theatres and |
| the arch's commemorative purpose, as on Trajan's | | | | amphitheatres. The Porta Aurea of Diocletian's Palace |
| Arch at Benevento and the Arch at Orange. That | | | | at Split, with arcaded entablatures above the entrance, |
| purpose was made explicit by a prominent inscription | | | | owed more to the traditions of the East, as is |
| on the attic storey above the archway. The whole | | | | emphasized by the great arcades and the Syrian |
| was surmounted by groups of sculpture, usually in | | | | pediment of the ceremonial courtyard within. |
| bronze. | | | | There is a clear military influence in the Palace's |
| The arched gate through a city wall might take much | | | | massive four-square walls, external towers, and the |
| the same form, but its function required that it should | | | | T-Junction formed by its colonnaded streets. |
| have guard chambers at the sides, often contained in | | | | Colonnades, and the peristyles of officers' houses in |
| projecting towers, and a gallery above, to allow | | | | military forts, were derived from what was familiar in |
| passage across the gateway. The window openings in | | | | civilian building. The plan of the headquarters, with its |
| the gallery might be given additional architectural | | | | courtyard and basilican hall, evolved in parallel with the |
| distinction by schemes of engaged pilasters or | | | | north Italian and Gaulish forum which it so much |
| columns, with pediments, as on the Porta dei Borsari at | | | | resembles. The decoration of the most important |
| Verona, or with a continuous entablature, as on the | | | | buildings in some legionary fortresses, like Neuss and |
| gates of Nimes and Autun. | | | | Lambaesis, gave them some architectural distinction. |
| Hadrian's Arch at Athens, which led from the old city | | | | Hadrian's Wall, by contrast, had the solid unembellished |
| to the new quarter, is unusual in the combination of its | | | | serviceability which characterized much military building. |
| decorative elements. The columns and pilasters of its | | | | |