The document discusses how geometry was used in the designs of four famous structures and works of art: 1) The Eiffel Tower uses specific shapes to make its tall, thin design stable and resistant to wind. 2) The architects of the Parthenon employed the Golden Ratio/Golden Mean in its beautiful design that has lasted over 1600 years. 3) M.C. Escher used tessellation to create repeating patterns with no gaps or overlaps in his work Strong Men. 4) Leonardo da Vinci incorporated the Golden Ratio in the proportions of the face in his famous painting the Mona Lisa.