This lecture focuses on Mies van der Rohe’s mature phase, especially his work after moving to the United States, where he refined his ideas of minimalism, structural clarity, and universal space. It explains how Mies translated his philosophy of “Less is More” into steel-and-glass architecture that emphasized order, proportion, and precision rather than ornament. The lecture discusses his role as Director of the Illinois Institute of Technology (IIT) and how the IIT campus became a laboratory for his architectural ideas, showcasing exposed steel frames, modular planning, and honest expression of structure. Key buildings such as Crown Hall, Farnsworth House, 860–880 Lake Shore Drive Apartments, and the Seagram Building (with Philip Johnson) are examined to explain concepts like universal space, clear-span structures, curtain wall systems, floating roof planes, and minimal detailing. The lecture highlights how Mies reduced architecture to its essentials structure, space, and material creating calm, timeless buildings that strongly influenced the International Style, corporate modernism, and high-rise architecture worldwide.