Sax Castle has Moorish origins (10th–12th century). It was conquered by the Crown of Aragon in 1239 and subsequently ceded to the Crown of Castile under the terms of the Treaty of Almizra. From its position, it dominates the whole city. The keep, whose foundations are laid over a cave, and the bastion tower are the elements that have survived to the present day.
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.