Kircher began research to find the origins of the ruins he had discovered, and concluded that the shrine had been built at the time of
Constantine the Great and commemorated the conversion of the Roman soldier Placidus, known to posterity as Saint Eustance. He then spent four years studying the site and its history, which culminated in a celebratory fete in 1664, followed by the publication of
Historia Eustachio Mariana the following year. These donations were secured partly through Kircher's account of how the shrine had originally been built by the Emperor Constantine and consecrated by
Pope Sylvester I, which had no foundation in evidence at all, and relied on Kircher's own idiosyncratic interpretation of an oak panel from the site. Overall, the claim of great age and illustrious founding for the shrine has been described as the "art historian Kircher at his most creative." and 700 scudi from
Pedro Antonio de Aragón, Viceroy of Naples. Other Catholic rulers from all over Germany also contributed. Having rebuilt and restored the chapel, Kircher added a device of his own design in the form of a set of large speaking trumpets that pointed at various villages in the valley below the shrine. These allowed the broadcast of calls to attend Mass to people several miles away. They were not described in
Historia Eustachio Mariana, but were illustrated in his later work
Phonurgia Nova (1673). ==Sections==