Construction on the Great Wall of China began as early as the 7th century B.C. and was continued by several different Chinese dynasties to protect the borders of the country from intrusion. It took hundreds of years to complete the Great Wall, which is over 21,000 kilometers long. Millions of prisoners were forced to work on the wall and it is believed that nearly one million lives were lost during its construction. Made of stone, brick and wood, this 2,000-year-old wall still stands today, attracting millions of visitors annually.
Sacsaywaman ' Peru
A stone fortress, Sacsaywaman is located in Cusco, Peru, once the capital of the Inca Empire. Considering that some of the stones used to make up this fortress weigh as much 200 tons, it's mind-boggling to think this structure was built even before the Inca Empire, around 900 A.D. to 1200 A.D. Even more impressive is the fact that stones were intricately cut to fit into one another very tightly, keeping the walls up for centuries without the use of mortar or grout of any kind. Sacsaywaman is believed to have been built by people who carried the stones from a quarry several miles away. Each stone is said to have been tied to rope, and pulled to its final destination. The masonry was so impressive that when the Spanish invaded and took over Cusco in the mid 1500s, they thought Sacsaywaman must have been built by demons and ordered it to be taken down. Much of it remains intact today, however, since many of the stones were simply too heavy for the Spaniards to move.