What do great cities do when they need space?

What do great cities do when they need space? They build UP. New York City does it. London does it. Portsmouth can do it. 

Thoughts of some in regional business looking for space and do not share that same imagination of building up. Sterile business parks with narrow options for transport - car and infrequent buses - shouldn't be at the top of the options to consider we say. Have some imagination, we say. With well connected transport and reuse of buildings, this is a more attractive option. Facilitating after work socialising and business and scientific forums, akin to Cafe Scientifique, where people and ideas can mix.