fortunes; for instance, the Arch of the Sergii was funded by Salvia Postuma, a female member of the family honoured, and the largest building in the forum at Pompeii was funded by Eumachia, a priestess of Venus. Slaves and the law At the time of Augustus, as many as 35% of the people in Italy were slaves, making Rome one of five historical "slave societies" in which slaves constituted at least a fifth of the population and played a major role in the economy. Slavery was a complex institution that supported traditional Roman social structures as well as contributing economic utility. In urban settings, slaves might be professionals such as teachers, physicians, chefs, and accountants, in addition to the majority of slaves who provided trained or unskilled labour in households or workplaces. Agriculture and industry, such as milling and mining, relied on the exploitation of slaves. Outside Italy, slaves made up on average an estimated 10 to 20% of the population, sparse in Roman Egypt but more concentrated in some Greek areas. Expanding Roman ownership of arable land and industries would have affected preexisting practices of slavery in the provinces. Although the institution of slavery has often been regarded as waning in the 3rd and 4th centuries, it remained an integral part of Roman society until the 5th century. Slavery ceased gradually in the 6th and 7th centuries along with the decline of urban centres in the West and the disintegration of the complex Imperial economy that had created the demand for it. Laws pertaining to slavery were "extremely intricate". Under Roman law, slaves were considered property and had no legal personhood. They could be subjected to forms of corporal punishment not normally exercised on citizens, sexual exploitation, torture, and summary execution. A slave could not as a matter of law be raped since rape could be committed only against people who were free; a slave's rapist had to be prosecuted by the owner for property damage under the Aquilian Law. Slaves had no right to the form of legal marriage called conubium, but their unions were sometimes recognized, and if both were freed they could marry. Following the Servile Wars of the Republic, legislation under Augustus and his successors shows a driving concern for controlling the threat of rebellions through limiting the size of work groups, and for hunting down fugitive slaves. Technically, a slave could not own property,