Almazán is a municipality located in the province of Soria, Castile and León, Spain. As of 2013, the municipality has a population of 5,843 inhabitants. It is also the seat of the judicial district of Almazán, and ecclesiastically it belongs to the Diocese of Osma, a suffragan diocese of the Archdiocese of Burgos. Connected via the Autovía A-15 and Carretera nacional N-111, it is situated 194 kilometres (121 mi) by road northeast of Madrid. The town lies on the east bank of the Duero river.

The Douro is the largest river of the Iberian Peninsula by discharge. It rises near Duruelo de la Sierra in the Spanish province of Soria, meanders briefly south, then flows generally west through the northern part of the Meseta Central in Castile and León into northern Portugal. Its largest tributary is the right-bank Esla. The Douro flows into the Atlantic Ocean at Porto, the second largest city of Portugal.