During its occupation of Britain (A.D. 43-410), the Roman Empire built an extensive network of roads. The Roman government recognized four categories of roads ranging in order from the most important to the least: public roads funded by the state; military roads built at the army's expense but also used by the public; local roads on which less engineering effort was expended; and private roads that were built and maintained by their owners. The latter two categories encompassed roads and tracks of varying quality. Before the Romans built roads, the ancient track ways of Britain had followed the natural terrain, seeking the easiest ground to traverse. Such tracks often detoured around marshy areas, hills, or ravines. Romans did not like to waste effort building long, meandering roads, so they ignored the older routes, preferring instead to move in the straightest line possible except where major obstacles in the landscape left no choice. Since Roman roads usually connected such new places of military importance as forts, towns, and administrative centers, the old track ways often did not take the desired direction. There were a few exceptions. Silchester was one of the pre-Roman centers of British activity reused by the Romans. There, the old native roads connected to the new road system.

Laying roads the shortest distance by going through obstacles required a great investment of labor. If a hill stood in the way, earth was hauled away until the land was leveled. If a wetland needed to be crossed, earth was moved in to build a causeway (raised road). Construction was systematic. A dependable road required a solid foundation. Roman roads were constructed with thick layers of tightly packed stones and gravel sorted for size. The larger stones formed the bottom layer, while layers of progressively smaller gravel filled in and leveled the roadbed. The final result was well over 30 centimeters thick and resistant to the wear and tear of heavy traffic and severe weather. More important roads were elevated above the surrounding land surface and provided with ditches on both sides so that the road surface would never flood. Elevated roads were so well fabricated they did not collapse or become rutted even in the worst rainy seasons. Upright curb stones buried in a line along the sides reinforced the road surface, keeping it stable. These elevated roadbeds formed the original highways of Britain and were much used until modern times.

Construction methods varied according to the official status of the planned road, but certain techniques were distinctly Roman. The careful layering and tight packing of selected gravels and other materials to form the roadbed is called metaling. Many different materials were used, depending on their availability and suitability to local subsoil conditions. Sand was added to keep the road from becoming too rigid and prone to cracking. In areas where iron ore was smelted into iron, the rock-hard chunks of slag, produced as a waste by-product during the smelting process, were added to the layering material. The iron content of the slag pieces had the added value of rusting over time. The rust would physically combine and harden with adjacent stones and sand to create an extremely solid, concrete-like mass. Heavily used roads were resurfaced from time to time. The final road metaling performed at the end of the fourth century sometimes resulted in a total road thickness of about a meter.

Roman roads in the fifth and sixth centuries continued to carry traffic, but roads do not choose their travelers. Historians speculate that the existing road system enabled a quick penetration of southeastern Britain by Germanic newcomers. The road system also allowed the entire population of Britain to move about in response to foreign threats and changing weather conditions. Townspeople left to the urban amenities of the European continent. Merchants sought markets and customers in safer jurisdictions, while farmers migrated to drier and warmer fields. The old Roman roads retained their importance in successive medieval centuries, too. Even where they did not remain in use as roads, the lines they imposed on the landscape often became boundaries for parishes and other significant administrative or private land units. The well-known Roman highway Watling Street in Northampton shire now serves as the line for a number of modern administrative boundaries.