I had my best ice cream ever in Gelateria San Crispino. After discovering it, I had to stop there each single day. Sometimes, a great ice cream replaced my whole meal.
Close to the Pantheon I tried once Giolitti, was also great. But I'm in love with San Crispino! Ice cream is cheap too in Rome compared to Paris and London - with a couple of euros you get a big cone with three flavours with whipped cream. I was amazed by the number of available flavours! I found this blog post which is useful for deciphering them.
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