Caulonia ( Kaulonia) is a comune (municipality) in the Province of Reggio Calabria in the Italian region Calabria, located about southwest of Catanzaro and about northeast of Reggio Calabria in the Stilaro Valley. Originally it was known as Castelvetere, but in 1862 the citizens decided to change the name of the town to that of the ancient city Caulonia. They believed that this city had been located on their territory, but it was eventually proved that ancient Caulonia was to be found near modern Monasterace, to the northeast.
Caulonia or Caulon (; also spelled Kaulonia or Kaulon) was an ancient city of Magna Graecia on the shore of the Ionian Sea. At some point after the destruction of the city by Rome in 200 BC, the inhabitants moved to a location further inland. There they founded Stilida, which developed into the modern town Stilo.
Since 1863 AD the name Caulonia has also been used by the city formerly known as Castelvetere. The city changed its name to Caulonia in honor of the ancient city, which was mistakenly believed to have been located in its territory. Today the ruins of the ancient city can be found near Monasterace in the Province of Reggio Calabria, Calabria, Italy. Some of the artefacts which have been excavated at the site can now be seen in the Monasterace Archeological Museum.