By Road and by Sea: Fastest Travel Times from Rome in the Roman Empire, with Itiner-e Roads, Pleiades Ports and Casson's Sailing Speeds

A companion study modelled travel from Rome over the Itiner-e network of Roman roads and found journeys of months: 210 days on foot to Carthage, because the road goes round North Africa. Here I add the sea. 211 ancient ports from Pleiades and the ancient voyage reports are joined to the roads and to a grid of 29,351 sea cells of 15 km covering the Mediterranean, the Black Sea and the Atlantic coast to Britain. Sailing speeds come from Casson's (1951) collection of ancient voyages and are calibrated to his Table 1 of 57 estimated sailing times between named ports: 5.2 knots running before the wind, 3.7 where my sources name no prevailing wind, and 1.0 to 1.6 knots dead into it, all within the ranges Casson gives. The summer etesian winds blow from the north in the Aegean and from the north-west in the central and eastern Mediterranean. The calibrated model falls inside Casson's range for 25% of the Table 1 passages and within a quarter of it for 63%, with a median of 1.01 times his estimate; a slower version that uses his median speeds and fits the speed into the wind to his 53 to 73 days from Alexandria to Rome manages 21% and 44%, with a median of 1.38. I headline the calibrated model, which matches the outward voyages that a journey from Rome mostly involves, and keep the slower one as a sensitivity test; the calibrated model makes the long voyage home from the east too quick. In summer, with the sea, Carthage is 5.8 days from Rome, Alexandria 12, London 30 and Constantinople 17 (36 with the slower model). The share of the provinces' land within 30 days of Rome on foot rises from 3.9% by road alone to 59%. Interactive version: https://maps.tristanhotham.com/roman-travel-times/. Data and code: https://github.com/Tristan-Hotham/roman-travel-times. Blog post: https://blog.tristanhotham.com/2026/10/31/roman-travel-times/. Companion study: Roads of the Roman Empire. Data: Itiner-e static version 2024 (de Soto, Pažout, Brughmans et al. 2025, https://doi.org/10.5281/zenodo.17122148), CC BY 4.0. Ports: Pleiades (CC BY 3.0). Provinces: Digital Atlas of the Roman Empire (DARE, Johan Åhlfeldt, CC BY). Sailing speeds: Casson (1951), TAPA 82, 136-148. Land: Natural Earth (public domain). Derived data, figures and text: CC BY 4.0. Code: MIT.