How can we find ATM locations in Milan, Venice and Florence?
ATMs are everywhere. I never look for them. Let them find me. On the days I decide I need an ATM I just start the day sightseeing. Often within an hour or so, I will see a bank and the ATM will be attached to the bank or inside a little room. Banks and ATMs are as common in Europe as in the US.
Try googling Banca Nazionale del Lavoro ATM and then the city name - all the cities you list have multiple locations.
You can also read more ATM tips at http://www.ricksteves.com/travel-tips/money. Buon viaggio!
Head over to http://maps.google.com and type "BNL atm near Rom Italy" into the search box and you're good to go.