Modern ruins are the remains of architecture constructed in the recent past, generally in the most recent century, or since the 19th century. The term is most frequently used by people performing urban exploration of man-made architecture that is abandoned or no longer accessible to the general public, such as structures abandoned through the process of urban decay. Enough documentation on these sites may have been lost over time that this unscientific exploration resembles archaeology of ancient ruins in the methods used to collect information.
High-profile modern ruins include amusement parks, grain elevators, factories, power plants, missile silos, fallout shelters, hospitals, asylums, prisons, schools, poor houses and sanatoriums.