Ruins

Ruins (from Latin ruina, meaning 'a collapse') are the remains of human-made architecture: structures that were once intact have fallen, as time went by, into a state of partial or total disrepair, due to lack of maintenance or deliberate acts of destruction. Natural disaster, war and depopulation are the most common root causes, with many structures becoming progressively derelict over time due to long-term weathering and scavenging.

There are famous ruins all over the world, from ancient sites in China, the Indus valley and Judea to Zimbabwe in Africa, ancient Greek, Egyptian and Roman sites in the Mediterranean basin, and Incan and Mayan sites in the Americas. Ruins are of great importance to historians, archaeologists and anthropologists, whether they were once individual fortifications, places of worship, ancient universities, houses and utility buildings, or entire villages, towns and cities. Many ruins have become UNESCO World Heritage Sites in recent years, to identify and preserve them as areas of outstanding value to humanity.

Cities
Ancient cities were often highly militarized and fortified defensive settlements. In times of war they were the central focus of armed conflict and would be sacked and ruined in defeat. Although less central to modern conflict, vast areas of 20th-century cities such as Warsaw, Dresden, Coventry, Stalingrad, Königsberg, and Berlin were left in ruins following World War II, and a number of major cities around the world – such as Beirut, Kabul, Sarajevo, Grozny and Baghdad – have been partially or completely ruined in recent years as a result of more localised warfare.

Entire cities have also been ruined, and some occasionally lost completely, to natural disasters. The ancient city of Pompeii was completely lost during a volcanic eruption in the 1st century AD, its uncovered ruins now preserved as a World Heritage Site. The city of Lisbon was totally destroyed in 1755 by a massive earthquake and tsunami, and the 1906 San Francisco earthquake left the city in almost complete ruin.
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