[jdietrich]

In central London, there are a large number of "iceberg houses", with basements far bigger than the original house. Strict planning constraints restrict development, but local authorities have been liberal in granting permission to develop below ground.

Many homes built by the super-rich have large areas with no natural light. Security concerns often limit window placement, and it is common to design the main bedrooms and living spaces to function as panic rooms with reinforced walls and doors.

I see a significant and lucrative market for this product.

http://www.theguardian.com/artanddesign/2012/nov/09/billiona...