Issued by Mexico in 1974, this commemorative marks 1 July – Día Nacional del Ingeniero (National Engineer Day), celebrating the nation’s engineering heritage. The design features the monumental Arcos del Sitio aqueduct at Tepotzotlán, State of Mexico, an 18th-century hydraulic and architectural masterpiece renowned for its soaring arches and technical ingenuity. Rendered in a striking blue palette with precise line work, the stamp highlights civil engineering achievement and historic infrastructure. A strong thematic choice for engineering, architecture, and Mexican landmarks collections.