The Livonian Order erected Grobiņa Castle in 1253 to protect the roads from Livonia to Prussia. It was a square type building and was a three storey high living block in the southern aisle. It also had a gate tower in the middle of the western wall. The castle was built of bricks and crude stone. Once it had arched ceilings. It was a residence for the local viceroy of the Livonian Order from 1399 to 1590. As support base in south Courland it was many times rebuilt and fortified.
In the times of the Duchy of Courland, the castle was destroyed and rebuilt many times. In the sixteenth and seventeenth century sand walls were erected around the castle. They had a bastion in each of the four corners and a stockade. Later the castle was used as a residence for local German landlords. The castle was destroyed in the eighteenth century. Many famous people have visited the castle, for example: Duke Jacob Kettler of Courland, The King of Sweden, Carl XII and the King of Prussia, Friedrich Wilhelm III.
In the 1970s major conservation jobs were made in the castle, so today the castle ruins are in a quite good condition. Most of the walls are still standing in three story height. Today's castle is a major tourist attraction and also a place for local gatherings and concerts.
The ancient Curonian castle hill (Skābāržu kalns) is located only 100 m from the castle. It is supposed to be the famous Seeburg, which is mentioned in Scandinavian sources already in 9th 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.