Recent research has revealed that the 12th century was a time of significant growth in the rural economy, with rising population levels and extensive tracts of new agricultural land being brought into production. The widespread construction of new rural churches is a strong indication that prosperity was being generated even in remote areas. A steady increase in population led to a higher population density in many areas of the empire, and there is good evidence that the demographic increase was accompanied by the return of a thriving network of revitalised towns and cities. According to Alan Harvey in his book "Economic expansion in the Byzantine Empire 900–1200", Archaeological evidence from both Europe and Asia Minor shows a considerable increase in the size of urban settlements, together with a ‘notable upsurge’ in new towns. For example, Harvey explains that in Athens the medieval town experienced a period of rapid and sustained growth, starting in the 11th century and continuing until the end of the 12th century. The 'agora' or 'marketplace', which had been deserted since late antiquity, began to be built over, and soon the town became an important centre for the production of soaps and dyes. Thessaloniki, the second city of the Empire, hosted a famous summer fair which attracted traders from across the Balkans and even further afield to its bustling market stalls. In Corinth, silk production fuelled a thriving economy.