The challenge of building below ground level sheds new light on all aspects of architectural and urban design. Any space that involves descending from our typical above-ground environment is a provocation to our sensory perceptions. Such hidden spaces evoke latent images of mythical dimensions, and they confront us with the clash between nature and artifice in our built environment. This book explores the character, use and design of underground space as a spaces of its own. International examples of commercial premises, restaurants, sports facilities, subway stations, museums, churches, libraries, concert halls, houses and other building types form the core material. Interviews with many renowned designers including Norman Foster, Emilio Ambasz, Floris Alkemade of OMA, Francine Houben of Mecanoo, John Carmody and other convey the views of the architects themselves on the subject. Various essays reflect on the cultural aspects, planning conditions, design considerations, technical requirements and sustainability aspects of building below ground level.