Geoagiu is a town in Hunedoara County, Romania, located on the Mureş river at an altitude of 217 metres above sea level.
The river with the same name flows in this place into the Mureș. The town has a population of 5,049. It administers ten villages: Aurel Vlaicu, Băcâia, Bozeș, Cigmău, Gelmar, Geoagiu-Băi, Homorod, Mermezeu-Văleni, Renghet and Văleni. Geoagiu is situated in the historical region of Transylvania.
The first settlements in the area can be found in the time of the Dacians, in the 1st century BC, as shown by archeological discoveries. After the Roman conquest, the Romans built the fort of Germisara in the 2nd century, however, it kept the original Dacian name. Germisara was defended by the Legio XIII Gemina.
The name of Germisara meant "hot water" and it showed that the Dacians already knew of the thermal springs of the area. Another opinion that the name came from the Hungarian name of the Geoagiu River, which means "curative".
The first documentary citation of Geoagiu was in the year 1291, when it was used as a land in the vicinity of Bintinti. At the 2011 census, 89.7% of inhabitants were Romanians, 8.81% Roma and 0.71% Hungarians.
There are remains of the old Roman way made of plate stones from Geoagiu to Geoagiu Băi. The city days are on August 14-17.