Piedras Blancas is the capital town of the municipality of Castrillón, in the province of Asturias, Spain. It is 5 km (3 mi) west of Avilés, 32 km (20 mi) west of Gijón, 40 km (25 mi) northwest of Oviedo and 6 km (4 mi) east of Asturias Airport.

Piedras Blancas is a singular entity of population and has the title of Villa.

Piedras Blancas, located in the parish of Laspra, is within easy access by motorway to the main urban areas of Asturias (i.e. Oviedo, Gijón, Avilés), and many of its residents commute daily to those areas.

Although not properly in the coastline, it is within walking distance from the beaches of Salinas, Arnao and Santa Maria del Mar. The climate is oceanic, characterized by mild winters and summers. Rain is frequent and may fall in any season, snow is rare.