The Khatt Shebib
In 1948, a wall running as far as 150 km, from north to south, was discovered in Jordan. Even though archaeologists first thought its purpose was protection against invading enemies, they quickly changed their hypothesis when they realized the wall was just over a meter tall when it was still complete. Even though no answers have been given conclusively, the wall is believed to have offered protection from animals that may have wanted to disrupt normal life.
Underwater Cairn
In 2003, Israeli archaeologists discovered a huge accumulation of stones under the Sea of Galilee near Tiberias in Israel. After much inspection, still no solid answers were brought to the table. What they did say was that all the stones together could weigh about 60,000 tons and that they were probably placed there as markings for burial plots way before the water levels rose to submerge the stones. The cairn probably dates back 4,000 years.