On its site of Quirinus Chapel was originally a heathen shrine which the Romans later worshipped as an early Christian sanctuary. Since the 11th century the site has been consecrated to Saint Quirin and from the beginning of the 13th, services were held in the two caves of the chapel. The Gothic pilgrimage chapel, partly hewn in the rock, was erected in 1355, while the roof and the small belltowers were added afterwards, at the end of the 19th century.
References:Herceg Novi was founded (on a former small fishing village, existing since Roman Empire times) as a fortress in 1382 by first Bosnian King Stjepan Tvrtko I and was called Sveti Stefan or Castelnuovo. The Turks conquered Herceg Novi in 1482, and ruled for 200 years, until 1687. However, there was a short pause between 1538 and 1539 when it was held by the Spaniards before they were defeated in the Siege of Castelnuovo. Turkey ruled again until 1687, from then until 1797, the town was ruled by the Venetian Republic.
The Herceg Novi old town is amazing. It is on a fairly steep hill that leads all the way down to the sea. Wandering through the small stairways to the various plazas and fortresses is a many hour adventure.