Gásir is an archaeological site north of Akureyri that preserves traces of a medieval trading place on Eyjafjordur. Before permanent towns dominated the region, seasonal markets like this connected Icelandic farms with merchants, ships, and goods from abroad.
The remains are subtle, so it helps to arrive with some context rather than expect standing ruins. For travelers with a car and an interest in Iceland's medieval economy, it is a worthwhile short detour from Akureyri.