Secrets of 10 world wonders

India’s Taj Mahal was built by Emperor Shah Jahan in memory of his wife and is one of the world’s most famous monuments. The minarets were designed to lean outward slightly, so that they would appear straight from ground level. Read more here.  (Vijay Mathur / Reuters )

Burj Khalifa. Dubai, UAE. This building, the world’s tallest, was designed with “wings” so that it could better withstand earthquakes and high winds. Read more here.  (Marco Brivio / Getty Images)

The Moai of Easter Island were apparently walked upright into place some distance from where they were quarried, using ropes and small teams of islanders. Read more here.  (Randy Curwen / Chicago Tribune)

England’s Stonehenge has been a mystery for centuries. The bluestones used to build this monolithic monument were likely floated part of the way to the site by raft. Read more here.  (Dan Chung / Reuters)

It takes 50 tons of paint to resurface Paris’ Eiffel Tower. Read more here.  (Jacky Naegelen / Reuters )

The Great Wall of China apparently can’t be seen from space -- only from low-Earth orbit and with a special lens, Lonely Planet says. Read more here.  (Frederic J. Brown / AFP/Getty Images)

Cambodia’s famous Angkor Wat temple is covered with more than 3,000 carvings of nymphs, each one unique. Read more here.  (Erik de Castro / Reuters )

Machu Picchu, Peru, was built with natural disasters in mind -- L-shaped building blocks and no mortar helped the buildings be more stable and avoid collapse in case of earthquakes. Read more here.  (Aurelio Alejo / AFP/Getty Images)

Petra, Jordan: This ancient site was probably carved from the top down, Lonely Planet says. Read more here.  (Muhammad Hamed / Reuters )