The story
From the ancient rumour that the Roman emperor Nero played a lyre during the Great Fire of Rome (AD 64).
Etymology from Wiktionary, CC BY-SA 4.0.
fiddle while Rome burns
Today it means: To neglect helping when one’s time is needed most; to ignore the major problem at hand (whilst doing something less important); to be idle, inactive, or uninterested in a time of great need. Full definition →