Ruins of Abandoned Building. Urban decay is the sociological process by which a previously functioning city, or part of a city, falls into disrepair and decrepitude. It may feature deindustrialization, depopulation or deurbanization, economic restructuring, abandoned buildings and infrastructure, high local unemployment, increased poverty, fragmented families, low overall living standards and quality of life, political disenfranchisement, crime, elevated levels of pollution, and a desolate cityscape, known as greyfield or urban prairie.