ORBIS - travel in antiquity
I don't know if this has been posted here before or not (I tried a search and couldn't find anything) or if this is the right thread (I hope so). Anyway this is a great page about travelling during the roman time. You can search on fastest, shortest and cheapest trip.
It is called ORBIS and is 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.
It is absolutely fantastic and gives you a lot of ideas on how to construct a world, from a travelling point of view.