The Eiffel Tower (built 1887–1889, engineer Gustave Eiffel):

• Made of wrought iron (not steel), formed into a lattice/truss framework.
• The open lattice structure minimises wind resistance while maintaining structural integrity.
• It was revolutionary in demonstrating that metal structures could achieve great height and elegance.
• It influenced the development of steel-frame skyscrapers in Chicago and New York.

This is a landmark in the history of structural engineering and architectural expression of structure.