Castellón or Castelló is a province in the northern part of the Valencian Community, Spain. It is bordered by the provinces of Valencia to the south, Teruel to the west, Tarragona to the north, and by the Mediterranean Sea to the east. The western side of the province is in the mountainous Sistema Ibérico area.

Castellón de la Plana , Castelló de la Plana , or simply Castellón / Castelló, is the capital city of the province of Castelló, in the Valencian Community, Spain, in the east of the Iberian Peninsula, on the Costa del Azahar by the Mediterranean Sea. The mountain range known as Desert de les Palmes rises inland north of the town.