Roman road glossary: 42 terms explained
Plain-English definitions of the words used about Roman roads: how they were built, how people travelled on them, and how to read the map and its sources. Every term with a page of its own shows what it means on the map and uses real figures from the Itiner-e atlas.
24 of the 42 terms have a page of their own. The rest are defined here, with a link to the page that covers them where there is one.
How roads were built
- AggerAn agger is the raised bank, or embankment, on which a Roman road was built.
- Are Roman roads still usedYes, in places.
- CamberCamber is the slight curve across the top of a road, higher in the middle and lower at the sides, so rain runs off into ditches.
- CausewayA causeway is a raised road or track built across wet or marshy ground. Roman builders marked the line with piles and sank stone between them to lift the road clear of the marsh, or used timber log roads where stone was scarce.
- Gravel road (via glareata)A gravel road, or via glareata, is a Roman road with a surface of packed gravel on a prepared base. It was cheaper than paving, and many Roman roads, including many in Britain, were surfaced this way.
- GromaA groma was a Roman surveying instrument: a horizontal cross with weighted plumb lines hanging from its arms, mounted on a staff.
- How Roman roads were builtRoman roads were built by surveying a line, clearing and digging a bed, filling it with stone and gravel, and finishing with a cambered surface and side ditches.
- MetallingMetalling is the hard surface layer of a road, made of small broken stones or gravel that were rammed down to form a firm, wearing surface. In Roman Britain it was often repaired and built up over many years, so excavated depths vary widely.
- Paved road (via strata)A paved road is a Roman road with a surface of stone slabs or blocks laid over a prepared foundation. Paving was more common in and near towns and on some major roads, while many Roman roads were surfaced with gravel instead.
- Road layers (statumen, rudus, nucleus)Road layers are the stacked courses of stone, gravel and sand under a Roman road surface. Ancient writers name layers such as statumen, rudus and nucleus, but real roads varied, and many British roads had a simple stone foundation under a gravel surface.
- Roman bridgeA Roman bridge carried a road over a river or valley, built of timber, stone or both.
- Roman surveyor (agrimensor)A Roman surveyor, or agrimensor, was a trained land measurer who laid out roads, boundaries and field grids using rods, a groma and measuring lines. For roads, surveyors set the line before the builders dug the bed.
- Who built Roman roadsRoman roads were built mainly by the Roman army's engineers and soldiers, supported by contractors, local labour and officials who paid for and oversaw the work. Repairs often fell to local authorities.
- Why Roman roads are straightRoman roads look straight because surveyors lined them up between high points that could be seen from each other, then built the road as direct as the ground allowed.
Travel and the state
- All roads lead to Romemap page"All roads lead to Rome" is a saying about the Roman road network, which really did radiate from Rome and join its provinces.
- Cursus publicusThe cursus publicus was the Roman Empire's state-run courier and transport system, created by Augustus to carry messages, officials and tax revenue between the provinces and Italy.
- Gallic league (leuga)The Gallic league (*leuga* or *leuca*) was a distance unit used in Gaul and longer than the Roman mile. Roman road distances in Gaul were often counted in leagues rather than miles.
- MansioA mansio was an official overnight stopping place on a Roman road, kept by the state for officials and others on government business.
- Milestone (miliarium)A Roman milestone (miliarium) was a stone column set beside a road, usually one Roman mile apart.
- MutatioA mutatio was a Roman changing station on an official road, where tired horses, mules or vehicles were swapped for fresh ones.
- ORBIS modelORBIS is a Stanford University model of the Roman world that works out the fastest, cheapest or shortest route between ancient places, using roads, rivers and sea lanes. It estimates travel time and cost, and it is separate from our map.
- Roman mileThe Roman mile (mille passus) was a thousand paces, about 1,479 metres by modern estimates, a little shorter than today's mile.
- Total length of Roman roadsmap pageThe Itiner-e atlas maps 299,171 km of Roman road in 14,769 segments across 39 countries, as the network stood around AD 150.
- Travel speed in Roman timesOn Roman roads, people on foot typically managed around 30 kilometres a day, ox carts rather less, and riders or state couriers much more.
- Via publicaA via publica was a Roman public road: a main road built and kept up at public expense, with its land vested in the state.
Reading the map
- Certain roadA certain road is Itiner-e's top class: a segment that is well documented in its sources and drawn to within about 50 m in mountainous terrain, or 200 m on plains. It is a solid line on our map, and only {fact:certainty.certain.pct} of the road length is in this class.
- Conjectured roadA conjectured road is a known Roman road whose course is drawn with lower accuracy because the sources say less about it. It is a dashed line on our map and the biggest class, at {fact:certainty.conjectured.pct} of the road length.
- HollowayA holloway, or sunken lane, is a road or track that lies well below the land on either side, worn down by water, traffic and time over a long period. Some old roads survive as holloways, but a sunken lane is not necessarily Roman.
- Hypothetical roadA hypothetical road is one Itiner-e has identified but not pinned down, or sits on ground where tracks were less fixed, such as deserts and flood plains, or is suspected with too little evidence. It is a dotted line on our map, at {fact:certainty.hypothetical.pct} of the length.
- Main road vs secondary roadIn the Itiner-e atlas a main road is a well-attested Roman route, backed by at least two of milestones, an ancient itinerary and a known major road.
- Road certaintyRoad certainty says how sure the atlas is about where a Roman road ran.
- Road segmentA road segment is one record in the Itiner-e dataset: a single line between two places or junctions, with its own length, type and certainty.
- Roman roads near memap pageTo find Roman roads near you, press Near me on the map.
Sources and data
- Antonine ItineraryThe Antonine Itinerary is a Roman register of stations and the distances between them along the roads of the Empire.
- CropmarksCropmarks are patterns in growing crops or grass that reveal features buried underground.
- How to find Roman roadsRoman roads are found by combining old maps and written records, aerial and lidar surveys, cropmarks and traces on the ground such as straight lines, banks, footpaths and place names.
- Itiner-eItiner-e is a free, open digital atlas of the roads of the Roman Empire, made by a research team including Brughmans, Pažout, de Soto and Bjerregaard Vahlstrup.
- Lidar and Roman roadsLidar is a laser survey, usually flown from an aircraft, that measures the height of the ground in fine detail.
- Margary numberA Margary number is the catalogue number given to a Roman road in Britain by the historian Ivan Margary.
- Pleiades gazetteeron romanempiremap.comPleiades is a free online gazetteer of ancient places.
- Ravenna CosmographyThe Ravenna Cosmography is a list of place-names from India to Ireland, compiled by an anonymous cleric in Ravenna around AD 700. It names many Roman places, but it is a text, not a map, and gives no road lines.
- Tabula PeutingerianaThe Tabula Peutingeriana, or Peutinger Map, is a medieval parchment copy of a late Roman road map.