Although the contract signed by Vandelvira set an execution period of two and a half years, his work actually took 26 years, which led to a new commission for Francisco del Castillo el Mozo [es], who undertook the construction of the vaulted ceiling over the choir, the enclosure of the west end and the completion of the loggia (or gallery) of the cloister with the addition of a fountain dedicated to Mary Magdalene, the patron saint of the priory.

Authors such as Fernando Chueca Goitia [es] have described the building as one of his most important works: [...] where Vandelvira renovated the church, creating a presbytery of great classical beauty and with certain traditional touches in the way of arranging the vaulting.

Decoratively, the church is in a pure classicist style, typical of the Vandelvira of the second half of the 16th century, with a Latin cross plan and a single nave, respecting the preferred forms of the Dominican Order.

In the corners of the ceiling of the main chapel are two squinches with shell alcoves, in which the arms of the priory's patrons Rodrigo Messía and Mayor de Fonseca are depicted again, flanked by angels.

On the other side of it, in the outer corner opposite the bell tower some traces remain of a previous structure (possibly a compass[clarification needed] or an unfinished construction), also leaving exposed to the open air the arches that support the aforementioned vault.

Finally, it is worth mentioning the artesonado ceiling, which survives in the sacristy but was looted from the rest of the bays, where the 16th-century brackets and ceramic plaques have disappeared (the latter were reinstated in the plinth of the main altar).

In the Plaza de Isabel II is a Renaissance fountain with five bronze spouts, the inscription on which reads: ESTA OBRA M[ANDÓ] FAZER EL ILL[USTRÍSI]MO SEÑOR EL MARQUÉS DON GONÇALO MESSIA CARRILLO MI SEÑOR AÑO D[E] 1566 ("This work was ordered to be made by the most illustrious lord the Marquis Don GONÇALO MESSÍA CARRILLO in the year of Our Lord 1566").

He was a preacher of the Order and also a relative of the lords of La Guardia who, in exchange for burial within the walls of the future priory church, from then on became the patrons and promoters of this work.

When work began on the residence of the lords, the castle-palace, they called the master mason of Jaén, Juan Rodríguez de Requena, the documentary evidence of whom begins in 1538, according to the date of a letter of payment.

The texts indicate that he could not read, but Juan Rodríguez was the material executor of much of the construction on the priory, serving as the essential link that united the various projects and architects who signed his plan.

Only one year after this letter of payment to Rodríguez de Requena, the work was suspended, and then transferred to a peripheral area far from the castle, near the fertile plains of the Guadalbullón [es] river, where a large orchard could be planted, while the friars remained in the residence of the lord.

El Salvador was private religious architecture, a true funerary pantheon for De los Cobos family, and it is not surprising that it aroused great admiration among all the nobility.

The name of Francisco del Castillo "El Mozo", who had built for the marquis the commemorative fountain in the Plaza de Isabel II and the bell tower of the parish church on the castle grounds, came to mind and he was called to the Dominican priory.

He arrived at La Guardia around 1570 to finish the cornice of the main chapel (an object of the 1564 contract that Vandelvira was unable to comply with) and the doorway of the church, as well as the upper gallery of the cloister loggia, an additional room and decoration of the convent.

In 1576, the last documented year of contracting work, he managed to settle the cornice while at the same time building two exterior buttresses at the east end to help take the weight of the vault on the structure.

Equally attributable to Castillo is the vault that closes the west end, with a relief of the Virgen del Rosario, very much related to his work on the third section of the church of Huelma.

As for the cloister, he added the start of new arches on the sides to prepare for the other bays to be completed in the future, which would never be done, as the Dominicans now prioritized functionality over pure ornament, a new decision that highlighted a lack of economic resources and a need to end the construction.

Six years later, when the archaeological museum of the Instituto de Estudios Giennenses was created in the lower galleries of the Provincial Palace, the fountain was moved to its current location.

[17] The sculpture of Mary Magdalene bears a stylistic relationship to the allegories of Justice and Prudence that Castillo executed in the same year of 1577 in building the old jail and the town hall of Martos.

In it, Christ was having dinner at the house of Simon the Pharisee when Mary Magdalene entered and knelt at Jesus' feet, which she washed with tears, dried with her hair, kissed, and anointed with the perfume that she carried in a glass of alabaster, whereupon she was redeemed with the words: "Her many sins are forgiven her, for she has loved much".

Regarding De Quesada, because of the nature of his contract, Soledad Lázaro believes that he was the one who made the coffered ceiling of the northeast wing of rooms, beautifully decorated with 26 brackets, of which today there are only three, the rest having been looted.

Therefore, it is more probable that, instead of making the coffered ceiling of the northeast wing, Miguel De Quesada rather elaborated the decoration of the upper floor of the cloister loggia, which was not finished and therefore not yet covered.

[20] Late in the 20th century, the construction of an oil mill, occupying the cloister and the eastern buildings, dedicated to the refectory and annexes, and the permanent abandonment of certain parts of the complex, led to the ruin of numerous elements.

The northeast wing, containing common rooms and cells, was partitioned, transforming the space into a dwelling and warehouse for a flour factory, with which the mill (attached to the east end of the church) was associated.

In 1962 and 1979 restoration work was carried out on the church, especially the replacement of the roofs and various decorative additions of different levels of success, such as the incoherent coloration in the tracery and the mouldings of the coffers that structure the vaults, as well as the misguided inserts in the attempt to beautify the unfinished west front.

{1566}: Inscription on the cartouche of the Plaza Isabel II fountain, in commemoration of the fact that Gonzalo Messía Carrillo was elevated to the title of Marquis of La Guardia in that year.

According to Soledad Lázaro, the documentary date of the contract was 1574, and in 1569 there is only evidence of his work on the bell tower of the Church of Santa María in La Guardia Castle.

(1576): End of the documentary record of the works of Francisco del Castillo "El Mozo" {1576}: Date on frescoed "phylactery" (in the sense of a scroll of text) on the second floor of the northeast corridor of the convent, located above the door that connected this room with the northern staircase of the church.

- 1160), who used it as a symbol of the union of the Old and New Testaments: Quos anguis tristi virus mulcedine pavit; hos sanguis Christi mirus dulcedine lavit.

{1680}: Inscription on top of coat of arms of the Order, the only remainder of the original gate of the main door, currently in sections and relocated on the front of the choir: SE HIZO ESTE CANZEL SIENDO PR[IOR] EL M[UY] R[EVERENDO] P[ADRE] P[ROVINCIAL] F[RAY] IVAN BUENO AÑO DE 1680.