Insula dell'Ara Coeli
The Insula dell'Ara Coeli is a rare surviving example of the multi-storey apartment blocks that housed most of Rome's urban population, and its ancient street level — far below the modern city — makes Rome's accumulated historical layers physically visible.
Roman insulae were vertically stratified by class — ground-floor spaces were commercial and desirable, while upper floors were smaller, cheaper, and far more dangerous.
The Insula dell'Ara Coeli was continuously reused across centuries — medieval structures were inserted directly into the Roman fabric, showing the building's long life well beyond antiquity.