Hobro is an old market and railway town in Region Nordjylland on the Jutland peninsula in northern Denmark. It has a population of 12,191. The town is situated in a hilly terrain at the head of Mariager Fjord, close to the former Viking fortress of Fyrkat. It is the seat of Mariagerfjord municipality.

Fyrkat is a former Viking ring castle in Denmark, dating from c. 980 AD. It is located near the town of Hobro, some distance from the present end of the Mariager Fjord in Northern Jutland. The fortress is built on a narrow piece of land, with a stream on one side and swampy area on the other sides. Likely built during the reign of Harald Gormsson or his son Sweyn Forkbeard, the fortress may have served as barracks or as a defensive stronghold. It would have help to enable control of the traffic on the main land-based trading route between Aalborg and Aarhus. Because of its unique architecture and testimony to the strategic power of the House of Knýtlinga, Fyrkat was inscribed on the UNESCO World Heritage List along with four other Viking ring castles in 2023.