Passage: During the reign of Augustus, the Celts living south of the Danube were conquered by the Romans. Around 40 AD, the first Romans settled on the site. This small town on the left bank of the Rhine was probably first called Drusomagus and belonged to the Roman province of Raetia. Its later name, originally Constantia, comes either from the Roman emperor Constantius Chlorus, who fought the Alemanni in the region and built a strong fortress around 300 AD, or from his grandson Constantius II, who visited the region in 354. The remains of the late Roman fortress Constantia were discovered in 2003.

Question: Where does Constantia's name come from?
either from the Roman emperor Constantius Chlorus