ATS Labs · Episode 16 · Open data, production-grade map

Antiquity Atlas

The roads and towns of the Roman world — 14,601 road segments, 1,186 named places, 19 legionary fortresses and 92 frontier walls — with the empire in 60 BC and at its greatest extent in AD 117, in 2D and on real terrain in 3D.

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The problem

Three open sources, none of them ready to map

The roads, the places and the frontiers of the Roman world are all published openly, by three different projects under three different licenses. Reading them right is where the time goes: almost none of the road segments carry a date, the road file arrives in a projection most web maps do not use, and the place dates are historical periods, not events.

Watch it work

Episode 16 — Antiquity Atlas (6:10)

Three open sources end to end: where the roads, places and frontiers live, the three details that cost the most time, and the 2D and 3D map they turn into.

What it covers

Three sources, three details, one map

  • The sources: the roads come from Itiner-e, an open digital atlas of Roman roads published in 2024 under CC BY 4.0, with 14,769 segments, each with a name, a type and how certain its course is. The places come from the Pleiades gazetteer of the ancient world under CC BY 3.0; Pleiades has no rank for importance, so the atlas keeps the cities with an ancient name and at least three recorded name forms, plus the forts named after a legion — 1,167 cities and 19 legionary fortresses. The frontier walls and the two empire outlines come from the Ancient World Mapping Center under the Open Database License, which is share-alike, so the derived files are published with the app. One script read all three on September 27, 2026.
  • Detail one, almost none of the roads carry a date: only 477 of the 14,769 segments have a usable construction date, about 3 percent, so a filter by date would hide most of the network in every era. Antiquity Atlas draws the whole network in both eras, and the era switch moves only the empire outline. The Mapping Center publishes outlines for 60 BC and AD 117 but none for the reign of Augustus, so nothing in between is drawn by hand.
  • Detail two, the roads arrive in World Mercator: the road file is in EPSG:3395, a projection measured in meters on the ellipsoid — not the Web Mercator of most web maps, and not longitude and latitude. The build script converts every vertex to longitude and latitude and simplifies each line to about 500 meters, finer than a pixel at empire scale.
  • Detail three, the place dates are periods: Pleiades dates each name of a place by the historical period it is attested in. The atlas keeps the earliest start and the latest end and caps later dates at AD 640, so Londinium reads 30 BC to AD 640 and 1,099 of the 1,186 places end at AD 640. The card states what the gazetteer records, not a founding date.
  • How it becomes a map: roads are bronze lines, with major roads first and minor roads from closer zoom; places are marble-white dots with Latin labels when the map is close enough to read them; the era switch crossfades the empire outline between 60 BC and AD 117; the search box finds a place by its Latin or its modern name; a place card gives the Latin, Greek and modern names, the type and the attested period; the fortress button shows the legionary fortresses as dark red squares and the frontier walls as dashed lines; a Grand Tour visits six cities; and a 3D view puts the roads on real terrain, where each road segment card gives its name, its class and its certainty — 12,855 conjectured, 1,040 certain and 706 hypothetical.

What it does not do

  • Not a dated road network — the roads are drawn the same in both eras because the open data dates only 3 percent of them.
  • Not a founding date for each town — the attested period is what the gazetteer records for the names of the place.
  • Not an official product of Itiner-e, Pleiades or the Ancient World Mapping Center — the data is theirs; the map and the app are All Things Spatial’s.

Where the data comes from

Every source in the episode

The roads are Itiner-e’s work under CC BY 4.0 and the places are Pleiades’ work under CC BY 3.0. The walls and empire outlines are Ancient World Mapping Center data under the Open Database License; the files the app derives from them are published with the app under the same license. The credits sit in the Antiquity Atlas footer, with Esri for the basemap.

Build with us

Need this on your data?

Antiquity Atlas is an ATS Labs build — TypeScript and React on the ArcGIS Maps SDK for JavaScript, over three open sources of the Roman world — and it is a demonstration of what All Things Spatial builds. The real thing — your data, your brand, your infrastructure — is the work we do for clients.

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