The Grotta del Mitreo is on the sloped of Mount Ermada, above the area where the river Timavo comes out after disappearing underground in San Canziano in nearby Slovenia and following an as yet unknown underground route of about 38 kilometres. This small sanctuary is dedicated to Mitra, who is a God of Indo-iranian origin who was accepted by the Roman legions and who was a cult object from the end of the first century until the advent of Christianity. The site was destroyed in the 5th century, but there are still some votive areas and side benches (where the initiates sat during the ceremonies) which can be seen. Temples weren't usually built in this area, it was more common to worship these divinities in natural caves or by water courses, as is the case here1.
See also
- http://www.igougo.com/attractions-reviews-b33868-Trieste-Grotta_del_Mitreo.html
- http://www.tertullian.org/rpearse/mithras/display.php?page=supp_Italy_Duino_Mithraeum