The tower of pisa Random Corner

•The Great Wall of China is the longest man-made structure ever built, measuring about 13,200 miles long. The wall took 200 years to build, and was erected primarily to protect China from attacks by northern tribes such as the Mongolians. Most of the original wall no longer exists because it is constantly being restored and rebuilt due to its age.

•Petra in Jordan, which has been used as a location for numerous films — including Indiana Jones and the Last Crusade — might seem like a fictional place, but it’s very real. This massive city built into sandstone was once home to around 10,000 people.

•The Colosseum in Rome is one of Italy’s most visited attractions. Dating back to around 80 B.C.E., it remains the largest amphitheater in the world. The structure was built by tens of thousands of slaves with stone and concrete, and can seat about 50,000 spectators. In its heyday, the Colosseum hosted events like gladiatorial combats, animal hunts and simulated naval battles.

•The Mayan city of Chichen Itza was built between the ninth and 12th centuries C.E. It was home to around 50,000 inhabitants covering five square kilometers.

•Machu Picchu in Peru is an ancient Incan citadel constructed in the mid-1400s, going undiscovered by Europeans until 1911. The granite stones used to build the site were either pushed up the mountain or chiseled directly from its slopes.

• The Taj Mahal in India is a marble monument commissioned in 1632 by Mughal Emperor Shah Jahan as a tomb for his favorite wife, Mumtaz Mahal. The construction took 20 years to complete and cost the modern equivalent of almost $1 billion.

•The most recently built wonder of the world is the statue of Christ in Brazil, which was completed in 1931. The 98-foot-tall statue is made of clay pieces, which were shipped to Brazil from France to be remade with reinforced concrete, then covered with 6 million stone tiles. Fun fact: Workers often carved secret messages onto the backs of the tiles before their installation.