Underground bases are facilities built below the Earth's surface, often used for military, research, or storage purposes. These structures can provide protection from natural disasters, surveillance, and enemy attacks. They are typically constructed with reinforced materials to withstand external pressures and are equipped with essential utilities like electricity, water, and ventilation. Many countries have developed underground bases for various reasons, including national security and scientific research. Some notable examples include the Cheyenne Mountain Complex in the United States and Dugway Proving Ground for biological and chemical defense research. These bases often remain classified to protect sensitive information and operations.