Considering the extreme congestion of population, no other solution than this is possible if Rome is to remain Rome. There is a great profit in building these huge, ungainly “islands,” the tenement blocks. Everywhere around the city we meet the gangs of laborers mixing the concrete whereof the structures are mostly constructed, or setting the wooden molds to shape the material as it solidifies; or else tearing down and carting away the wreckage of insulæ that have begun to decay. Such property employs a great amount of capital. Nearly every senator has his men of business caring for his housing investments and rentals, and the “realtor” is a very familiar personage. Rightly is it complained also that many insulæ are put up in a cheap and absolutely dangerous manner, and at best are dark, dirty, and unsanitary. The very name implies that they should be built with a free space all around them. The old law of Twelve Tables (450 B.C.) required a passage way (_ambitus_) of at least two and a half feet on either side, but this law was recklessly disregarded until the great fire of Nero enabled the government to enforce a fairly scientific building code. Even now, however, the tenement houses are often hemmed in on all sides by miserable black alleys hardly accessible to the public scavengers. This struggle to use every scrap of ground is completely matched by the effort to build as high as possible. “The immense size of Rome,” wrote Vitruvius, about 1 A.D., “makes it needful to have a vast number of habitations, and as the area is not sufficient to contain them all on the ground floor, the nature of the case compels us to raise them in the air.” There are no passenger elevators in Rome; furthermore, the concrete construction does not permit the safe erection of extremely high buildings without unusual precautions, and with such narrow streets tall structures obstruct both light and air; nevertheless, the real estate interests grumbled loudly when Augustus limited the height of dwellings to seventy feet. Hadrian has just vexed them still more by a decree that if an owner allows his insula to fall into dangerous repair, he must either sell it, or rebuild it thoroughly. For all that, many insulæ seem to be towering rookeries, ready to collapse at any flood or earthquake. =27. A Typical Insula.=--Upon Mercury Street, which we have just examined, stands a very average insula, built about forty years ago, and, therefore, loyally named the _Flavia Victoria_ for the then reigning dynasty. It belongs to the widow of the rich eques Gaius Macer, and is managed by the lynx-eyed procurator, or bailiff, who superintends her estate. Despite the fact that it is safer than some of its neighbors, the tenants complain on rent days that the upper stories are built so largely of wood as to be in peril of fire, and that one of the outer walls is so cracked that it has to be propped up with heavy timbers.