According to AC lounge list there is no *G lounge in Rome.

If you're flying business or first (dont know if that exists ex Rome) or as *G passenger in economy, on a *A carrier, I expect the airline has made other lounge arrangements.

Edited to add the LH lounge tool gives the answer as

[quote]
Airport Rome - Leonardo Da Vinci
Location Terminal B, above the Gate B9
Opening hours 06.15 - 20.30 L.T.

Lounge Types
Contract Lounge
Name of Contract Lounge I mosaici
Combi-Lounge

Lounge Access
Star Alliance Gold cardholder
Senator
First Class
Business Class