Saskia Sassen is the Robert S. Lynd Professor of Sociology and co-chair of the Committee on Global Thought, Columbia University ( www.saskiasassen.com).

FORBES: The Global City And The Global Slum

Saskia Sassen, co-chair on the Committee on Global Thought at Columbia University and a leading expert on smart cities, draws parallels with the office buildings of the sixties, which she describes as "low-ceiling places now standing sad and empty as advanced technologies render them useless".

BBC: How will our future cities look?