The Planetari de Castelló is a cultural centre for scientific and technological education located in the Grao de Castellón, the maritime district of Castelló de la Plana. It was inaugurated on 8 May 1991, becoming at the time the second planetarium of its kind in Spain and the first in the Valencian Community. It is managed by the Castellón Town Council.

The building stands out for its large white dome, 25 metres high, visible from the seafront against the blue of the Mediterranean. It has four exhibition halls, conference rooms and a projection hall. Inside, it houses a Foucault pendulum as an interactive scientific demonstration. It also hosts the information centre for the Columbretes Islands Nature Reserve, with an exhibition hall dedicated to this volcanic archipelago.

The outdoor space is equipped with an armillary sphere sundial, a wind rose and the sculpture 'Hembra del Mar' by Castellón sculptor Juan Ripollés, which presides over the main entrance to the building. All of this is integrated into an open-air garden that forms part of the exhibition complex.

Since its opening, the Planetari has organised multiple editions of the Astronomy Days, which have become established as a national meeting point for amateur astronomers and educators. The centre is a point of reference for astronomical and scientific education in the province of Castellón.

The building is located at Paseo Marítimo no. 1 of the Grao de Castellón (postcode 12100), at the start of the Litoral Park which extends northwards, with the port of Castellón to the south. It is managed by Jordi Artés and is open Tuesday to Sunday during morning and afternoon hours, with closure in September.