§193. The next change took place in the city and town house only, because it was due to conditions of town life that did not obtain in the country. In ancient as well as in modern times business was likely to spread from the center of the town into residence districts, and it often became desirable for the owner of a dwelling-house to adapt it to the new conditions. This was easily done in the case of the Roman house on account of the arrangement of the rooms. Attention has already been called to the fact that the rooms all opened to the interior of the house, that no windows were placed in the outer walls, and that the only door was in front. If the house faced a business street, it is evident that the owner could, without interfering with the privacy of his house or decreasing its light, build rooms in front of the _ātrium_ for commercial purposes. He reserved, of course, a passageway to his own door, narrower or wider according to the circumstances. If the house occupied a corner, such rooms might be added on the side as well as in front (Fig. 40), and as they had no necessary connection with the interior they might be rented as living-rooms, as such rooms often are in our own cities. It is probable that rooms were first added in this way for business purposes by an owner who expected to carry on some enterprise of his own in them, but even men of good position and considerable means did not hesitate to add to their incomes by renting to others these disconnected parts of their houses. All the larger houses uncovered in Pompeii are arranged in this manner. One occupying a whole square and having rented rooms on three sides is described in §208. Such a detached house was called an _īnsula_.