Space and Time. The Roman empire was roughly the same size as the continental United States. The distance from the far northeastern corner to the southwestern one, when the empire was at its height, was roughly the same as from Boston to Los Angeles, with one big and obvious difference: the Romans had in their center a huge sea, the Mediterranean, meaning, literally, "in the middle of the lands." This large body of water, with its predictable periods of relative calm during the summer and its lack of tides, greatly facilitated movement within the empire. The central location of the capital city, in the middle of a peninsula that jutted out into the middle of the sea, makes it no surprise that the Romans frequently referred to the Mediterranean as mare nostrum (our sea). They were never more than...