The hermitage of Sant Nicolau de Bari stands on Carrer Alloza (formerly calle d'Amunt) in Castellón de la Plana, on the site once occupied by the mosque of the city's medieval Moorish quarter (morería). Its foundation dates from 1536, when the Christian community transformed the Islamic space into a place of Catholic worship under the patronage of Saint Nicholas of Bari.

The building is catalogued as a Property of Local Relevance (Bien de Relevancia Local, BRL). Its typology corresponds to the urban hermitage of late medieval origin, integrated into the historic fabric of the old town.

The building's link to the former mosque of Castellón's Moors makes it a direct testimony to the religious and urban stratification that followed the expulsion and conversion of the Mudéjar population in the sixteenth century, a process common in Valencian towns following the decrees of forced conversion of 1526.

The hermitage is located in the historic centre of Castellón, close to the urban axis that links the Plaza Mayor with the neighbourhoods of medieval expansion. Carrer Alloza still preserves part of the network of narrow streets inherited from the Islamic period.

The façade is simple, characteristic of the sixteenth-century repopulation hermitages of the Valencian region, without major external ornamentation but of notable historical value due to its continuity of use since the medieval period.