Ruins are the remains of structures that have fallen into disrepair or been destroyed over time. They can include buildings, monuments, and other constructions that once served a purpose but are now partially or completely collapsed. Common examples of ruins are ancient temples, castles, and cities that provide insight into past civilizations. These remnants often attract historians, archaeologists, and tourists who seek to understand the history and culture of the people who built them. Ruins can be found worldwide, from the Colosseum in Rome to the Machu Picchu in Peru, showcasing the architectural achievements of different eras.