Fort Bokar is part of the Dubrovnik city walls, and has been around since the 14th century. The reinforced stone walls are referred to as one of the Middle Ages most fortified constructions, having never been breached. This is one of the filming locations of the King’s Landing City Walls in Game of Thrones.
Fort Bokar can be seen when Tyrion and Lord Varys have a discussion surrounding the best approach to protect King’s Landing as they gaze into the distant sea during season 2. In this same location during season seven, Cersei Lannister explains to her brother Jamie that she is planning to join forces with Euron Grayjoy.