The Duero rises in the Picos de Urbión Mountains in the northern Spanish province of Soria at an altitude of 2,080 meters. It flows through the autonomous community of Castile and León, passing through the cities of Soria, Almazán, Aranda de Duero, Tordesillas, and Zamora. For 112 km, it forms the Spanish-Portuguese border, with the river landscape on both sides located in protected natural parks: Arribes del Duero and Douro Internacional. From here, it flows 213 km into Portugal, passing through the cities of Miranda do Douro, Pinhão, and Peso da Régua, as well as the Alto Douro wine region. The Duero flows into the Atlantic near Porto and Vila Nova de Gaia.