The Planetari de Castelló is a cultural centre for scientific and technological outreach located in El Grao de Castellón, the maritime district of Castelló de la Plana. It was inaugurated on 8 May 1991 and, at the time, was the second planetarium of its kind in Spain and the first in the Valencian Community. It is managed by the Ayuntamiento de Castellón (Castellón City Council) and directed by Jordi Artés.

The building is distinguished by a large white dome 25 metres high, visible from the seafront. It has four exhibition rooms, lecture halls and a projection room. Inside there is a Foucault pendulum as an interactive scientific demonstration, as well as the information centre for the Columbretes Islands Nature Reserve, with an exhibition room dedicated to this volcanic archipelago.

The outdoor space is laid out as an open-air garden that forms part of the exhibition complex. It features a sundial with an armillary sphere, a wind rose and the sculpture 'Hembra del Mar' (Sea Woman), by the Castellón sculptor Juan Ripollés, which presides over the main entrance.

Since its opening, the Planetari has organised numerous editions of the Jornadas de Astronomía (Astronomy Days), which have become a national meeting point for amateur astronomers and educators. The centre is a leading reference for astronomical and scientific outreach in the province of Castellón.

It is located on the Paseo Marítimo del Grao de Castellón, at the start of the Parque Litoral, which extends northwards, with the Port of Castellón to the south. It opens from Tuesday to Sunday, morning and afternoon, and closes in September.