Though the castle itself is just an elaborate CGI masterpiece, the breathtaking setting where the show films is completely real — and it's free to visit.
Located near Bermeo, Spain, the site is known as San Juan de Gaztelugatxe and was originally built as a religious hermitage by the Knights Templar in the ninth century. A church sits atop the tiny island, accessible only by a narrow set of stairs that bridge the island to Spain's mainland.
While the monument and staircase never close to the public, getting there can be tricky. Not only is it about an hour and a half drive from the closest town, but the trek up the mountain is far from easy. The path is straightforward, thanks to the island's status as a popular tourist destination, but it's a steep hike and not recommended for anyone not in good physical condition.