The real thirds or decimal thirds were an income granted by the Church to the Crown of Castile and later to the Hispanic Monarchy, consisting of two ninths of the ecclesiastical tithes . Over time it became a regular income for the Crown, which in many cases ended up alienating it to try to alleviate the always meager Royal coffers. This also happened in Baena , where the thirds were alienated in favor of the Duke of Sessa, constituting until the confiscation processes of the 19th century, one of its largest and most healthy income.

The abundance of this payment in kind required a suitable building to store everything that was collected as tithes and thirds, beginning the works in 1792 and ending three years later. This is how the Casa de la Terciaarose, one of the largest baroque buildings of an agricultural nature in Andalusia, which remained active until 1841 when, after the suppression of ecclesiastical rents due to the Confiscation of Mendizábal, the building was sold at public auction, serving from that moment on as inn, tenement house and even party prison in the first months of the civil war. Already in much more recent dates, the town council, after having rented it as a municipal warehouse, acquired it and after its restoration began to use the old barns as a House of Culture while the winery with jars and annexed rooms would be recovered later for the headquarters of the Commonwealth of Municipalities of Guadajoz and other administrative dependencies. Finally, in February 2011,Historical and Archaeological Museum of Baena for whose use the entire building is used today.

The main façade , in which there are numerous symmetrical openings protected by thick bars, stands on a high stone plinth and is decorated with a trompe l’oeil imitating padded ashlars. In the central part it has a Baroque doorway with a split pediment from which you can access the customer service area, room I and the wide stairs that lead to the upper floors. In the background is a large porticoed patio.Undoubtedly, the most characteristic element of the architectural complex, where trompe l’oeil is once again the protagonist, simulating garlands, balustrades and other architectural elements. The first two floors are porticoed on three sides, with semicircular arches on stone and brick pilasters, while the third has a gallery that runs around the entire perimeter and supports its roof on small iron columns with their respective footings. . Around these galleries open the different rooms and dependencies of the Museum, being especially relevant the lower floor covered with groin vaults.