Fortification refers to the process of strengthening a structure to protect it from attacks or natural disasters. This can involve building walls, towers, and other defensive features around a city or important location. Historically, fortifications were crucial for military defense, helping to keep enemies at bay and safeguard the inhabitants within. Famous examples include the Great Wall of China and the forts of medieval Europe. In addition to military uses, fortification can also apply to food. This involves adding essential nutrients to enhance its nutritional value. For instance, many cereals are fortified with vitamins like B12 and minerals such as iron to help improve public health.