The Carlist Wall, also known as the Castellón Carlist Wars Walls, is the name given to the remains of a wall that stood in Castellón de la Plana, in the Plana Alta region, in the first half of the nineteenth century, possibly in 1837. It is located in the city centre, along what is known as the Liberal Wall.

It is classified as an Asset of Cultural Interest by generic declaration, with ministerial annotation number R-I-51-0008996 and date of annotation December 15, 1999, as recorded in the General Directorate of Artistic Heritage of the Generalitat Valenciana.

Castellón de la Plana was besieged by Carlist forces in July 1837, as the town remained loyal to Isabel II during the Carlist Wars and was thus besieged on several occasions by General Cabrera's troops. This compelled its inhabitants to construct new walls. They were demolished around 1855 after the danger had passed, but were rebuilt during the Second Carlist War (1873-1874).

Only a few remnants of the 1837 wall remain today, with no connection to the mediaeval wall and a moat, six gates, and some batteries.

The remains in the Plaza de la Muralla Liberal, in particular, were part of the Batera del Gas (Gas Battery), an artillery bastion. This new wall extended to the west of Castellón, covering what are now known as the Magdalena and Mijares ring roads, eventually reaching the well-known San Francisco gateway; to the east, the walled enclosure extended along Guitarrista Tárrega street, the lower part of Gobernador street, and finally Moreres street, eventually reaching the San Roque gateway.

Other remains have been documented by archaeological excavations in the city, some of which can be found in the Plaza Dolçainer de Tales and others between Calle Prim and Calle Marqués de la Ensenada. The former have allowed for the documentation of a section of the Carlist wall moat that runs north-east to south-west across the square. It has also been possible to document the existence of an irrigation channel dating back to the 14th century, known as the Coscollosa irrigation channel.