Borgarvirki, (“Citadel”) (177 m) a group of rocks on the ridges between the Vesturhóp district and the Víðidalur valley, with basalt columns 10-15 m high and a circular depression at the top, open to the east. There a big stone wall has been raised, through which is the entrance. The wall and others nearby were repaired in 1949-50, and in the depression are the ruins of huts and a well. Nobody knows why Borgarvirki was made. One story is that Víga-Barði in Heiðarvíga saga intended it as a defence against attack from the people of the Borgarfjörður district, another that it was the work of Finnbogi rammi in Finnboga saga ramma. View dial.