That worldbuilding is complicated and time-consuming is something every creator of fiction, no matter the media adopted, knows well. Creating detailed and coherent fantasy worlds or alien civilisations is hard. But even historical fiction, especially when taking place in eras far away from the present, can be a complex task. You have the advantage of sources, true. But you have a peculiar challenge: since things have happened, everybody can know about them more than you, and spot a fake detail in your otherwise perfectly crafted fictional universe. Ouch! (As somebody that loves, and write, alternate history, I know too well that feeling – and fear).
So, apart from the always valid suggestion of only giving few, important details – which seems a good thing in any convincing worldbulding (check out William Gibson if you harbour any doubt in merit), the suggestion is to research, research and then research even more.
So imagine my delight when, checking different sources online to estimate a realistic travel path in Roman times, I ended up finding ORBIS.
Otherwise said: “The Stanford Geospatial Network Model of the Roman World reconstructs the time cost and financial expense associated with a wide range of different types of travel in antiquity. The model is based on a simplified version of the giant network of cities, roads, rivers and sea lanes that framed movement across the Roman Empire. It broadly reflects conditions around 200 CE but also covers a few sites and roads created in late antiquity.”
Incredible, isn’t it? But wait, it gets better. You can actually input your coordinate, way of travel, preferred routes and meteo. Amazing. That’s what a simulation looks like:
As explained in the help online, the model consists of 632 sites, most of them urban settlements but also including important promontories and mountain passes, and covers close to 10 million square kilometers (~4 million square miles) of terrestrial and maritime space. 301 sites serve as sea ports. The baseline road network encompasses 84,631 kilometers (52,587 miles) of road or desert tracks, complemented by 28,272 kilometers (17,567 miles) of navigable rivers and canals.
And if you wonder why water lanes have been made so accurately, there’s a historical answer for this; it was the favourite way of travelling of rich Romans – roads where either for soldiers or quite dangerous.
ORBIS has (unsurprisingly) got an excellent reputation and The Atlantic wrote about it too, claiming that, thanks to similar tools, “rather than encounter history as a linear story, we see it as a world more like our own, one in which we’re actors with sets of competing choices laid out before us.” (The Atlantic, 23 May 2012). I certainly concur.
For a more extensive treatment of this topic, you may want to check out Lionel Casson, in Travel in the Ancient World (here a section on Google Books) and these good posts (1) and (2) about travel in Roman times, while, for a reading about Roman roads, this is a good starting point. Happy worldbuiding!