The largest Iron Age ring fort in Sweden, Gråborg was built as the Roman Empire was crumbling. Its impressively monumental walls measure 640m around, even though much of the stonework was plundered for later housing. After falling into disuse, the fort sprang back to life around 1200, when the adjacent St Knut’s chapel (now a ruin) was built. The Gråborg complex is about 8km east of Färjestaden; you need your own transport to get there.
