Castellón de la Plana 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.
The first known building in the area was the Moorish castle of Fadrell, near the Alqueries de La Plana. The town proper was officially founded in 1251, after the conquest of the Moorish Kingdom of Valencia by King James I of Aragon in 1233. James granted royal permission to move the town from the mountain to the plain on September 8, 1251, and tradition claims that the move was completed by the third Sunday of Lent, 1252. During the Middle Ages, the city was protected by moats, walls and towers, and a church was built, later becoming a cathedral. In the 17th century the town was one of the last strongholds in the Revolta de les Germanies (local guilds). It also supported Archduke Charles of Austria in the War of the Spanish Succession (1701–14), but was later taken by the troops of Philip d'Anjou.
In the 19th century, the city walls were torn down and it slowly began to expand, a process interrupted by the War of Independence against Napoleon (1804–14) and the Carlist Wars (1833–63). In 1833 Castelló became the capital of the newly constituted province. In the second half of the 19th century, the city again began to expand, marked by the arrival of the railway, the enlargement of the port and the construction of representative buildings (Provincial Hospital, Casino, Theater) and parks.
In 1991 a university (Jaume I University) was established, set upon a modern campus. The local economy is based on industry, tourism and craft-work.