Insula or a Roman tenement house was the place of residence of ordinary citizens of Rome. Insulae were buildings with an area of 300 to 400 square meters and a height of 15 to 20 meters. The tenement houses had several floors, and the walls were full of windows and doors overlooking the streets, which usually surrounded them on four sides. The walls had to be at least 45 cm thick.
During the early empire, Rome was indeed the centre of the world. Not because at the Forum Romanum there was the Navel of the World (Umbilicus Mundi) in the form of a round temple, not because at the Golden Milestone (Miliarium Aureum) all roads of the then civilized world. Rome was then the largest city, and thus the most densely populated city. Historians estimate the number of inhabitants in this period at 1 million on an area of approximately 2,000 hectares. No wonder rents, land and house prices were sky-high. In fact, in the days of Octavian Augustus, living in Rome could be afforded either by very wealthy citizens or by those ready to endure all the inconvenience of living in tenement houses.
For about 1,700 patrician villas there were about 45,000 tenement houses in Rome with apartments for rent.
The house of a wealthy citizen sometimes occupied a much larger area than an insula. It was a closed complex, at most one-story, with no windows on the side of the street. The height of the floors and the thickness of the insula walls were regulated by strict building standards and legal regulations. This was to prevent collapsing houses from being built hastily from collapsing. Unfortunately, due to the often low quality of building materials, such accidents happened quite often. Octavian introduced a limit of five floors. After the great fire of 64 CE, Nero introduced a new solution that prohibited the construction of insula higher than 7 floors. Trajan then lowered that ceiling to six stories.
The second serious threat to the inhabitants of tenement houses was fire because the apartments were heated with bronze wood stoves, illuminated with oil lamps and even torches, while the tenements were largely built of wood (ceiling beams, stairs, shutters).). In order to minimize the effects of the fire, Nero ordered to leave 3-meter gaps between tenement houses. These breaks were to prevent fire from spreading to neighbouring buildings. In addition, he ordered the installation of special platforms for firefighters, and also ordered the erection of buildings from materials more resistant to fire. Only Trajan ordered the construction of houses from fire-resistant materials.
On the ground floor of the insula, there could be shops, usually one-room ones, or the owner’s apartment. The stairs to the upper floors led straight from the street, and the comfort of the apartments (coenacula) decreased with the height. It is true that as comforts decreased, so did the rent, but it was not a great consolation. The top storeys looked more like makeshift cubicles than living quarters.
However, the owner did not always live in his tenement house. Very often their owners were Roman patricians, who in this way gained another source of income. Insulae on their property were handled by specialized administrators (insularii), liberators or slaves living in a given tenement house. They acted as administrators, i.e. they collected rents, dealt with repairs, kept order, etc.
Only the residents on the ground floor had access to running water and sanitary facilities. The premises on the higher storeys were already deprived of this. Their inhabitants used baths and public latrines. Potties were also a popular device, the contents of which were often thrown out of the window onto the street.
Water for everyday needs was brought from fountains or wells in the yard. Each insula also contained an adequate supply of water in large clay or brown containers (dolia), stored in case of fire.
Some of the best-preserved insuliae are currently in Ostia.