How is it possible to find someone who you only saw briefly and who you don't even know? Can the internet hel?

I saw a very beautiful, suntanned lady in Siena, Tuscany on May 11th this year. She was wearing a blue dress and had short dark hair. She was eating an icecream when I spoke to her. She said the ice cream was very good and that I should try one. She was either American or British? I believe she was around forty years of age? Does anyone know her or was anyone in Siena on that day who might know her?