How did the Romans know which direction to build their roads?

The long-running series in which readers answer other readers’ questions on subjects ranging from trivial flights of fancy to profound scientific conceptsWhen the Romans started building a new long–distance road, how did they know exactly in which direction to go? A small error at the beginning of construction would leave them miles out at a distant destination. Yet all their major roads are straight.Rodney Gentry Continue reading...