At the beginning of the 18th century, the Order of the Blessed Virgin Mary of Mercy (Mercedarian Friars) conceived of a great basilica in honour of Our Lady of Bonaria.
The original planner for the project was Antonio Felice De Vincenti, a military engineer who designed it in the Piedmontese baroque style.
After several interruptions, they began again towards the end of 18th century, this time entrusting the task to the tutelage of De Vincenti's pupil Giuseppe Viana, also a military engineer.
The new supervisor was not keen on his master's plan, however: the idea of the great baroque Basilica was, therefore, abandoned for a more sobre classical construction.
Inside the Basilica, near the entrance door, a series of texts and photos document the history of the church, showing how it looked before and after the restructuring.