Ancient monuments and heritage sites face a diverse array of threats that can lead to irreversible structural and aesthetic decay. Environmental factors are among the most persistent, including "acid rain" caused by air pollution which eats away at limestone and marble, and "salt crystallization" which shatters stone from within. Climate change is an accelerating threat, bringing rising sea levels that endanger coastal sites (like those in Venice or Alexandria) and extreme heatwaves that cause thermal expansion and cracking. Human impact is equally damaging, ranging from the "vandalism" of graffiti and theft of artifacts to the "over-tourism" where the breath and sweat of millions of visitors increase humidity in enclosed spaces like tombs or caves, promoting mold growth. Urban encroachment and industrial development often lead to the vibration of nearby traffic or construction, which can weaken ancient foundations. Finally, armed conflict and political instability remain catastrophic threats; many sites in the Middle East and Ukraine have been intentionally targeted or used as military outposts, resulting in the total destruction of "Outstanding Universal Value" that survived for thousands of years prior to modern warfare.