La Lonja del Cáñamo (Hemp Exchange), Calle Caballeros no. 1 in Castellón, is a building built in the 18th century in the Baroque style and expanded in the 19th.

This structure is located in the city centre, near the Plaza Mayor square. The Lonja was built in the first third of the 17th century after the city council purchased the Casa Gumbau, which was demolished in 1605 to make way for the new structure. Francesc Galiança designed it. It is also referred to as "la Llotja del Cànem."

It is a quadrangular structure with two arches supported by Tuscan columns and semi-columns on the free sides. The town coat of arms, the only sculptural element, is located between the spandrels of the arches on Calle Colón. The structure is made of ashlar masonry.

The town council sold the right to build an upper floor at the beginning of the nineteenth century. The lower floor was also extended on both sides, with the same material and architectural language used. The upper floor has rectangular windows with curved pediments set in corbels and elliptical oculi above. The balcony in the corner with wrought ironwork is especially impressive.

It is known that Oliet painted allegorical paintings on the façade of this floor. A classical cornice with ovals and a parapet topped with vases crown the ensemble.

The Universitat Jaume I purchased the building in 1999 and used it as an exhibition hall between 2002 and 2005 after an emergency refurbishment due to its poor condition. Finally, on February 27, 2007, the fully restored Lonja was inaugurated as the Universitat Jaume I City's headquarters. Since then, it has served as a cultural centre, hosting exhibitions, talks, debates, and courses, as well as housing the offices of the Universitat Jaume I's Society of Friends and Alumni.