Borgarvirki is a volcanic plug in North Iceland that has been used as a fort by the Vikings throughout history. Standing at 177 meters above sea level, it offers stunning views of the surrounding area. With its columnar shape and strategic location, it was a perfect spot for early Vikings to defend themselves. The site has been renovated over the years, and visitors can explore ruins of human habitations and a freshwater well within its walls. Don't forget to check out the nearby Hvítserkur rock formation and seal colonies on the Vatnsnes Peninsula while you're there!