The Great Pyramid of Giza. The Great Wall of China. The Parthenon. The Eiffel Tower. Stonehenge. Great structures capture our imagination and give us a lasting collective heritage. (They also provide the backdrop to innumerable selfies.) But while they may last for centuries, these familiar objects have widely divergent building times. Some take decades to erect, others just a few years. Still others have been slowly created over centuries. Here are some of the world's most famous landmarks, along with the time it took to make them a reality.