Malta: Mnajdra Prehistoric Temples
Reminiscent of Stonehenge, these stone structures from the Copper Age (3600-2500 B.C.) are the oldest freestanding megaliths in the world. They predate even Egypt's Pyramids—and their age is showing. Many are collapsing because of rain, salty sea breezes, and vibrations from nearby quarries. Even more heartbreaking is the lack of security, which has left the temples open to vandals who recently overturned 60 stones and etched graffiti on them.
Turkey: Ani Archaeological Site
Ambling from the ruined bridge to the crenellated defense wall and proto-Gothic cathedral, you'd never guess that this medieval ghost town once rivaled Constantinople in power and glory. Its crumbling state is certainly due to natural causes (Ani was built in a seismic zone), but because it has the misfortune of being an Armenian heritage site in Turkey, government officials aren't too concerned about its deterioration. Ani has been the victim of looting and acts of destruction over the years, and reports indicate that concrete is being used to replace the stone, making proper conservation of this 1,100-year-old city impossible.
Ethiopia: Mentewab-Qwesqwam Palace, Gonder
The buildings in Ethiopia's former capital are in various states of decline, but the most delicate among them is the Mentewab-Qwesqwam Palace, commissioned in the 18th century by Queen Mentewab. It's a prime example of Gonderian-style architecture, a hybrid of Portuguese, Indian, and Ethiopian influences. Owing to decades of neglect, however, the palace roof has caved in, walls have eroded, and pools of water have destroyed the foundation.
Egypt: Valley of the Kings, Thebes, Luxor
Most of the wall paintings in the tombs still have rich colors and distinct lines, despite the fact that they can be traced back as far as the 16th century B.C. While there are numerous threats to these world-renowned monuments, the greatest is tourism. About 1 million visitors throng the passageways every year, and unless the flow of traffic is curtailed and railings are built to protect the frescoes from oily hands, they will continue to be damaged every day.