The document discusses the history and development of windmills. It notes that vertical axis windmills first originated in Mesopotamia and China around 700 BC and were introduced to Europe by Crusaders. Horizontal axis windmills were designed by Heron in the 1st century AD and became widely used in Greece due to strong wind resources. Greek windmills were typically two-story stone buildings that housed the drive system upstairs and grain grinding and storage downstairs. While over 6,000 windmills existed in Crete in the early 20th century, many have now been abandoned and fewer than 1,000 remain today mainly for tourist purposes.