A year or two ago (or more -- time flies), I stumbled across a web site showing (I think) common routes (of communication and post, I think, but might have been trade) in the ancient Roman world. It was a live web site in that you could pick an origin point and the map would update to show where you could go in a day, three days, two weeks, two months, etc. Does that sound familiar to anyone? I can't seem to just Google it up. I know this isn't really a question ABOUT history, but I'm guessing there are enough interested people here that somebody might just know (as opposed to Quora or StackOverflow or HackerNews).