This Portuguese definitive stamp, valued at 5 escudos, depicts the Aqueduto das Águas Livres (Aqueduct of the Free Waters), a monumental engineering feat supplying Lisbon with water since the 18th century. Built between 1731 and 1799 under King João V, the aqueduct is renowned for its elegant Gothic arches and resilience—it famously withstood the 1755 Lisbon earthquake. The design captures the aqueduct’s sweeping arches stretching across the Alcântara valley, highlighting both architectural grace and historical importance. Issued by Correios de Portugal, this stamp celebrates one of Lisbon’s most iconic landmarks and a triumph of early modern engineering.