common perception has the common man living in a city

The "common man," whatever exactly we want that to mean, did not live in the city but in the country. The majority by far of the Roman world's population lived on small farm plots of a few jugera, either rented or owned.

probably with stone buildings

Most insulae were made mainly out of brick, sometimes stuccoed. But the city was notorious for shoddy, unsafe buildings. Surviving insulae like those at Ostia give the misinformed impression of neat, solid, well-built structures with thick walls and abundant space between adjacent buildings and the street. The insulae at Ostia are, however, not typical, but conform to late antique building codes that did not exist during most of the Roman Period and which, after their introduction, were not usually enforced at Rome, which was far too populous and crowded for such things to work. In reality the Roman urban day-laborer, who with his peers made up most of the urban population, lived in poorly-built tenements of uncertain safety. Rubble faced with brick or marble was a common, cost-saving means of construction, and buildings collapsed with alarming frequency--in a surviving letter Cicero mentions that one of his owned buildings collapsed, and remarks that he can now build it better and charge more rent. Urban insulae were also frequently made of highly flammable materials, not stone, and fire was a constant danger in the city. Insulae had no hearths, and thus the urban dweller was forced to cook his meals (usually consisting of little but puls, a sort of emmer porridge mash) out of doors. Nevertheless, insulae caught fire easily from lamps and other hazards, and the flammable construction ensured that fire spread rapidly. Insulae within the city (unlike at Ostia, where it was prohibited) frequently shared walls with the buildings next door, a habit still seen in Rome and throughout Italy today. Fire spread naturally, therefore, from one building to the next. Moreover, insulae often had overhanging roofs, which projected out over neighboring buildings and the alley-like streets, spreading fire further--the Roman jurists debated whether embers falling from an overhanging roof were grounds to demolish a neighbor's building without the risk of lawsuit, since demolition was the most common and safest method of preventing the spread of fires.

The life of the rural farmer depended to a degree on the period, but a pre-modern farmer is a pre-modern farmer. Rural dwellers worked their little plots, paying their rents (usually in kind) if necessary and selling the surplus. A variety of crops were grown in Roman Italy, although grain by far was the most common agricultural product--livestock was also common, although herding sheep or cattle usually required access to pasture. Like all pre-modern farmers the Italian farmer was at the mercy of the weather, and a bad growing season could be disastrous to these small farmers, forcing them to take out loans that might never be repaid or even sell off their property and head to the city. The Romans themselves, especially Appian, spoke of a land crisis of the second century, when supposedly wealthy individuals violated the laws limiting the occupation of the ager publicus, the public land on which many unlanded Romans and Italians took up rented plots, and either established large estates on public land or actually renting them out. However, archaeologically there's very little evidence of a shrinking independent farmer class, pushed off their land by expanding estates--small-time farming communities actually increase in number at the end of the Republic and the beginning of the Principate.