Friday, October 10, 2014

How Big is that Town?

Urban Population Density in Antiquity
I like the world building aspect of gaming. That's probably the biggest attraction for me to being a DM is to be able to create campaigns and settings. But one of the unanswered questions in all of the RPG materials I have picked up over the years is how big is the town? Not in terms of population size, that goes back at least to AD&D, but in terms of area. Not surprisingly, this is dependent on the type of civilization you are modeling. As Scheidel says concerning urbanization rates in his paper Roman population size: the logic of the debate "we must allow for the possibility that direct analogies between urbanization levels in antiquity and in later periods may simply be irrelevant because they seek to equate conditions in two very different environments: Greek and Roman societies, with their poleis and civitates that fused cities with their respective hinterlands, [than] post-Roman Europe, with its much more pronounced boundaries between city and countryside" Given that caveat, I did some research based on the area figures of classical cities mostly from Ancient Town Planning by Francis Haverfield, generate a correlation between population and area that can then be used as a guideline when constructing urban areas.

For those of you who would prefer not to wade through the numbers below the jump, heres the outcome.
Cities - 326 persons per hectare or 330 ft2 per person
Towns - 233 persons per hectare or 462 ft2 per person

Note that this includes roads, alleys, public buildings and spaces, so the actual size of living quarters will be much smaller.

Cities are entered multiple time due to finding multple estimates of area and population.
NameArea (ft2)Populationft2/
Persons /haPopulation Source
Nicea in Bythnia5,760,0002000288374Wiki
Nicea in Bythnia5,760,0003000192561Wiki
Lincoln1,800,0006,000300359www.localhistories .org/lincoln 
Autun21,344,40050,000427252Roman Cities by Pierre Grimal
Trier30,666,24050,0003rd Century613176Roman Cities by Pierre Grimal
Trier5,227,2002000261341Roman Cities by Pierre Grimal
Trier5,662,8002000283138Roman Cities by Pierre Grimal
Silchester4,356,0002000217849Roman Britain and English Settlements by Robin George Collingwood, John Lowell Linton Myres
Silchester4,660,9202000233046Roman Britain and English Settlements by Robin George Collingwood, John Lowell Linton Myres
Caerwent1,742,4003000580185BBC Occupation of Wales
Caerwent1,960,2003000653165BBC Occupation of Wales
Sirmium28,836.8157,0000.51212,766Lives Behind the Law: The World of Codex Hermoenionus - Serona Conolly
Sirmium10,763,900257,000188570Lives Behind the Law: The World of Codex Hermoenionus - Serona Conolly
Ostia7,427,091327,000275391Roman Corinth: An Alternative Model of the Classical City - Donald Sykes
Pompeii6,888,896310,500656164Roman Corinth: An Alternative Model of the Classical City - Donald Sykes
Corinth53,819,500352,0001035104Roman Corinth: An Alternative Model of the Classical City - Donald Sykes
Corinth + Lechaian78,038,275372,000108499Roman Corinth: An Alternative Model of the Classical City - Donald Sykes
1 - Area from panacomp.net. Travel site, far too small for any of the population estimates. Suspect that it refers only to the actual dig site.
2 - Area from The City in Late Antiquity by Dr John Roth
3 - Area from Roman Corinth: An Alternative Model of the Classical City - Donald Sykes

Looking at the data, I could see that some of it just didn't fit. Especially the area for Smirium from the panacomp.net travel site. I concluded that it probably refers to the actual dig site, not the area of the Classical town which was at one point one of the capitals of the Tetrachy. The population density was simply impossible, even 16th century Venice didn't exceed the range of 450-510 persons per hectare.  On the other end of the scale was Silchester, a well documented site in England where the inhabitants either all lived in what the banking business calls Single Family Dwellings rather than the insulae common to the Roman urb or else contained a considerable amount of grazing/garden land with in the site.

Removing records with population densities above 700 and below 50 persons per hectare, I constructed the following graph.

Metropolises are all over the board for population density, but considering that two of those cities (both Neapolis entries) are based off of my best guess rather than any population data I found, they're not really worth anything.

The smaller cities and towns do cluster, first tightly at the 70-100 persons per hectare area.and then more loosely from 150-400 persons per hectare. My hypothesis form looking at which data points were in each group, was that the lower cluster indicated a roughly standard colony foundation and construction where the town site had been laid out with an eye to future population growth,  The second group would then represent mature, stable communities.

And that's where I left my analysis, because I found that to quote Douglas Adams, it wasn't "worth a load of dingo's kidneys" to continue.  For one thing, with the exception of some recorded population sizes of the initial colonizing parties, most Classical urban population figures are calculated from the area of the ruins.  So all I have been doing is reversing the calculation.  In addition, I had stumbled across a paper that had done the analysis with a great deal more rigor than I would be able to.  In his study A New Perspective for the Demographic Study of Roman Spain, Monfort performs a more complete analysis of the available data and provides the figures of 326 persons per hectare for large urban centers and 236 persons per hectare for smaller centers.   Both of the figures fall with in the my range of 150 - 400 for mature urban centers.  In applying them to games systems, whatever population sizes the system defines as cities or metropolises will use the large urban center value, while anything defined as a town will use the smaller value.


  1. Fascinating.Worrying over stuff like this is why I almost never manage a decent historical game. I spend all my time on research and never come up with an adventure!

    1. That is the seductive aspect of world building. I've had it lead to analysis paralysis more than once. Which is why I'm trying a fill in the blank approach, but perhaps I should turn that into its own post