"Theories serve as the foundation for understanding and solving complex problems in infrastructure development and construction. Discuss the importance of theory in civil engineering, emphasizing its role in structural analysis, materials science, and fluid mechanics. Explore how theoretical principles inform the design process, ensuring structural integrity, safety, and sustainability. Additionally, elaborate on the evolution of key theories in civil engineering, highlighting notable contributions from historical figures and contemporary researchers. Evaluate the significance of theoretical advancements in addressing modern challenges such as climate change adaptation, urbanization, and infrastructure resilience. Provide examples of how theoretical knowledge is applied in real$-$world civil engineering projects to enhance efficiency, durability, and cost$-$effectiveness."