Guys, this is not a security issue.
It is a LEGAL issue, and according to where you go, it can be a big one.
If you go to Italy with bags of undocumented cash and they find them, you'll most likely find yourself in hot water.
For the Italian gov, undocumented cash in good quantities = tax evasion.
Cover your butt and be careful with cash, esp. if there's no paper trail.