30. The human and material foundations

Industrialisation was the key factor in the city’s growth and modernisation from the 18^th century onwards. This was especially the case in the first third of the 20^th century due to the diversification of activities resulting from innovation in power sources and technology.

Mass immigration, the outcome of rising demand for labour, posed new challenges for the city such as social and cultural cohesion and housing. Backed by its long commercial tradition, Barcelona became a great European industrial metropolis and in the late 20^th century had to tackle new issues such as urban metabolism and sustainability policies.