The Order, being the owner of the masterly church Santa Maria della Steccata, originates from Costantino emperor's militia.

The first time this Order has been mentioned dates back to 1551, when the Pope Giulio III with the papal bull "Quod Alias" bestowed the title of "Gran Maestro" to Andrea and Angelo Comneno, who claimed to be descendant of the great Costantino. The building is an outstanding Renaissance model, at the hands of Bernardino Zaccagni with a remarkable influence of Leonardo. Its fascination also grabs the attention of experts, for another notable personality is thought to be part in the process of setting-up, "Il Bramante". The exhibition of the Ordine Costantiniano's artistic properties will definitely satisfy each visitor, for its many different fields of interest: cleric, pictorial, heraldic, silverware and textiles.