The Romans, who were skilful builders, used brick in all parts of their constructions. In the walls called "medium and small dressed," the masonry was formed of rubble enclosed between two facings of brick or ashlar-work, and comprising a variable number of alternate layers. Among examples of this class of construction may be mentioned: the Herculaneum gate of Pompeii, the fortified castle of Babylon in Egypt, and finally the hot baths of Caracalla, all works dating from the early centuries of the Roman Empire. From the 3rd century onwards this use of alternate layers of bricks and stones of various dimensions became more frequent; numerous Gallo-Roman buildings were constructed in this manner. Bricks alone or accompanied by key-stones form the arches of doors and windows. The Romans frequently used brick arches hidden in the thickness of the wall as a means of consolidating and distributing the pressure on certain points. They also made a general and remarkable use of arches of brick, or more frequently brick and rubble, to cover large spaces like the baths and the palaces of the Caesars.
Roman aqueducts also present examples of the use of brick in arches and facings. Such are the ruins of Nero's aqueduct at Rome, and the aqueducts of Lyons, Aries, Mayence, etc.
For interiors, brick masonry was generally covered with stucco, and such materials were even used for building isolated columns as has been shown in the basilica at Pompeii. Finally, combinations and arrangements of bricks have been used by the Romans for pilasters and cornices to adorn several buildings of ancient Rome.
The history of human arts shows that, whatever may be the nation, country, or epoch, they pass through three periods: development, apogee, and decadence. This is what happened in the case of Roman brick-building. The apogee was reached in about the 1st century A.D., contemporaneously with the first emperors; then came the decadence, which was marked by the little care given to the construction of masonry. While the joins were scarcely visible in the fine ancient edifices, now they gradually increase until at last masonry came to be composed of materials of all shapes and dimensions. The thickness of the joins is a means of ascertaining the age of Roman monuments, and is found by counting the number of bricks in a given length: in the 1st century there were 10 bricks in .3 metre (arcades of Nero); in the 2nd century, 8 bricks (Adrian's villa); in the 3rd, 6 bricks (Aurelian's wall); 4th century, 4 bricks (circus at Mayence).
In concluding this historical sketch of the use of bricks by the Romans, we need hardly add that remains of pottery are found in all parts of their immense empire.
The architecture of the Christian monuments, built almost everywhere between the 4th and 10th centuries, was inspired by that of the Romans; we frequently find the alternate use of bricks and stones or rubble, for example, in what remains of the walls of Saint-Laurent's Church at Rome (4th century), in the churches of the Basse-CEuvre, at Beauvais; of Vieux-Pont-en-Auge (Calvados); of Saint-Mcsmin (Loiret); of Saint-Martin d'Angcrs (9th century), etc. etc.