Castrillo de los Polvazares is a Spanish town that is part of the municipality of Astorga, located in the region of Maragatería, in the province of León, within the autonomous community of Castilla y León. In 1980, it was recognized as a Historic-Artistic Site due to its remarkable monumental value.

In 2015, during the extension by UNESCO of the Camino de Santiago in Spain under the denomination "Caminos de Santiago de Compostela: Camino francés y Caminos del Norte de España", Spain presented a "Retrospective Inventory - Associated Elements", where Castrillo de los Polvazares was included in n.º 1766, with a set of associated elements.

Traditionally, the inhabitants of Castrillo de los Polvazares were maragato muleteers, traders who were dedicated to the transport of products such as wine and fish, among others. The houses, known as casas arrieras, were designed for this activity, with large gates for the wagons, interior patios, stables and large warehouses.

Originally, the village was located elsewhere, but after being destroyed by a flood, it was rebuilt in its present location in the 16th century.

The Maragato muleteers played a prominent role in the area between the 16th and 19th centuries. Strategically located on the communication routes between the interior of the peninsula and Galicia, the Maragata region allowed the muleteers to transport salted fish from the Galician coast to the interior and return with sausages and dried products. However, the arrival of the railroad in Astorga in 1866 marked the beginning of the decline of this profession.

Until 1975, Castrillo de los Polvazares was an independent municipality, but then decided to join the municipality of Astorga. The village is a picturesque urban ensemble, with cobblestone streets that maintain their essence and traditional style, characterized by houses with stone facades, linteled or semicircular doorways, some with coats of arms, and wooden carpentry. The parish church, built in stone, also stands out. According to some sources, the name "Castrillo" comes from the proximity of two ancient settlements: Castro de San Martino and Teso de la Mesa.

Castrillo de los Polvazares was the setting chosen by the writer Concha Espina to set her novel "La Esfinge Maragata", where she renames the village Valdecruces. In addition, the French filmmaker René Clair has a link with this town, as his wife lived there until 2006.

In 2004, 2006 and 2018, Castrillo and Astorga hosted the Jornadas Napoleónicas, an event that commemorates the Spanish War of Independence. During these days, the attack and siege of the city of 1810 is recreated, with parades and staged battles in which the French and Spanish armies face each other.

The town has an old bridge over the Jerga River, built in masonry, but with several reforms over time. It also has a second bridge, built in the early twentieth century, which connects Astorga with Ponferrada and combines stone with metal elements.