Gaius Cassius Longinus was a Roman senator who was involved in the plot to betray and kill Julius Caesar. Based on the album’s many allusions to the Classics and biblical imagery, this song’s title is likely in reference to him.

Pecknold has also stated that the Cassius in question may refer to Cassius Clay (Muhammad Ali). This is confirmed by the song “I Should See Memphis”, which refers to both ‘Cassius in Rome’ (Longinus) and ‘in Kinshasa’ (Muhammad Ali, in the Rumble in the Jungle, in which Ali won the heavyweight title from George Foreman).