martyrdoms, almost all cemeteries were extramural. John Bodel found that three cemeteries of the Imperial era each had a "peak life" of between 150 and 200 years intensive use, involving perhaps 4 or 5 generations, before they were filled, and their land was repurposed. As cities and towns expanded beyond their original legal and ritual boundaries, formerly intramural cemeteries had to be redefined as "outside the city" with deeds and markers, or their burials moved, releasing much-needed land for public or private use. Among Rome's most disruptive and obtrusive building projects were its aqueducts, whose planning and construction involved extreme care in legal negotiation with landowners and landusers, and avoidance of damage, if possible, to tombs, graves, monuments, chapels and shrines. The emperor Aurelian's expansion of Rome's walled areas skirted these issues by incorporating sacred and religious places into the fabric of his new walls; some strictly unlawful destruction, however, would have been inevitable, and this was officially recognised and compensated. Where private and public interests collided, the law provided for restitution of loss to private parties, but not prevention. Rural villas and estates A likely majority of Romans (Hopkins, 1981, calculates 80–90%) spent their entire lives in rural poverty, working on farms and villa estates as tenants, free labourers or slaves. Wealthy landowners used the income from their farms to support town houses, military and political careers, and a lifestyle of cultured leisure (otium). While some affected to despise money, farming was represented as an entirely appropriate, intrinsically noble occupation. By the 2nd century BC, the monumental tombs of aristocrats were a part of the rural and suburban villa landscape, surrounded by tombs of lesser family members, outnumbered by the humbler tombs of the bailiffs, commoner-tenants, and slaves who ran the place. Far from the main roads between towns and cities, the graves of field-workers occupied poor ground not worth the planting or grazing; landowners could offer burial space on their own property for whoever they wished, and wherever they pleased; graves were sacred no matter where. In his capacity as a land surveyor, Siculus Flaccus found that grave markers at the edge of estates were easily mistaken for boundary markers (cippi). Many of the elite chose burial among their ancestors at the family farm and villa, until the emperor Marcus Aurelius banned the practice in an effort to limit the spread of the Antonine Plague (165 to 180