Encroachment, or the usurpation of public space by secondary structures, is nowadays considered indicative of economic prosperity. This opinion is largely based on laws and literary sources, whereas many archaeological remains are still categorised as the houses of squatters. This article considers mainly archaeological sources which show the evolution of encroachment throughout Late Antiquity. An overview of its topographical settings within the city and its connection to other buildings is offered, together with an assessment of its appearance and function. These elements are then used to establish the degree of public involvement in its construction and to explain the chronological and topographical spread of encroachment.