According to the Bible, Noah's Ark was a world-changing engineering feat, and it took cutting-edge construction to build it. Experts use the latest tech and modern-day science to reveal if building it a second time would be just as difficult.

The Great Wall of China is one of the world's greatest engineering marvels, and it took dangerous, cutting-edge construction to build it. Experts use the latest tech and modern-day science to reveal if building it a second time would be as deadly.