The cost to rebuild Rome was immense , requiring funds the state treasury did not have . Nero devalued the Roman currency for the first time in the Empire 's history . He reduced the weight of the denarius from 84 per Roman pound to 96 ( 3 @.@ 85 grams to 3 @.@ 35 grams ) . He also reduced the silver purity from 99 @.@ 5 % to 93 @.@ 5 % — the silver weight dropping from 3 @.@ 83 grams to 3 @.@ 4 grams . Furthermore , Nero reduced the weight of the aureus from 40 per Roman pound to 45 ( 8 grams to 7 @.@ 2 grams ) .