A complex structure refers to a system or organization that consists of multiple interconnected parts, making it intricate and often challenging to understand. This can be seen in various fields, such as biology, where the human body is a complex structure made up of organs, tissues, and cells that work together to maintain life. In architecture, a complex structure might refer to a building with various levels, rooms, and functions, like a skyscraper or a shopping mall. These structures require careful planning and design to ensure that all components function harmoniously, highlighting the importance of organization and integration in complex systems.