The Domitian highway after long preparations( 16) furnished a secure land-route from Italy to Spain, and was closely connected with the founding of Aquae Sextiae and Narbo;( 17) the Gabinian( 18) and the Egnatian (19) led from the principal places on the east coast of the Adriatic sea--the former from Salona, the latter from Apollonia and Dyrrhachium--into the interior; the network of roads laid out by Manius Aquillius immediately after the erection of the Asiatic province in 625 led from the capital Ephesus in different directions towards the frontier.

Of the origin of these works no mention is to be found in the fragmentary tradition of this epoch, but they were nevertheless undoubtedly connected with the consolidation of the Roman rule in Gaul, Dalmatia, Macedonia, and Asia Minor, and came to be of the greatest importance for the centralization of the state and the civilizing of the subjugated barbarian districts.
In Italy at least great works of drainage were prosecuted as well as the formation of roads.

In 594 the drying of the Pomptine marshes--a vital matter for Central Italy--was set about with great energy and at least temporary success; in 645 the draining of the low-lying lands between Parma and Placentia was effected in connection with the construction of the north Italian highway.
Moreover, the government did much for the Roman aqueducts, as indispensable for the health and comfort of the capital as they were costly.

Not only were the two that had been in existence since the years 442 and 492--the Appian and the Anio aqueducts-- thoroughly repaired in 610, but two new ones were formed; the Marcian in 610, which remained afterwards unsurpassed for the excellence and abundance of the water, and the Tepula as it was called, nineteen years later.

The power of the Roman exchequer to execute great operations by means of payments in pure cash without making use of the system of credit, is very clearly shown by the way in which the Marcian aqueduct was created: the sum required for it of 180,000,000 sesterces (in gold nearly 2,000,000 pounds) was raised and applied within three years.