The violin was invented in Italy in the 1500s (during the Renaissance). The idea that Nero “fiddled” during the Great Fire, which happened in 64 A.D., is ridiculous. If such a thing even happened he would have played the cithara.
The reason for the slur about him playing during the fire is usually misinterpreted nowadays as a metaphor for Nero being too entitled or callous to care about the suffering of lower people. But that’s slathering modern politics over Roman insults. The Romans, despite inheriting a rich musical tradition from the Italians, Greeks and Etruscans, maintained a cultural attitude that practicing music was an effeminate hobby. The actual message in the “Nero fiddled while Rome burned” myth is that the Romans wanted history to know that they thought Nero was off being a girly-boy during the crisis.