Ok, which one gets your vote and why?

Verda's Cafe in Burwell, Nebraska. Verda is a great cook, and it's just like mom used to make (if your mom was a great cook). And very inexpensive--all you can eat pancake special just 99 cents. Her pot roast and bread pudding are to die for. Haven't been back to visit the relatives in a couple of years now, but just thinking about that bread pudding is making me salivate.

Anyone else?

I like the atmosphere at the Cafy Real across from the Palacio Real in Madrid. A few seats have great views of the Royal Palace and it is a perfect place to meet local madrileyos and a few fellow travelers.

MMM

For poshness it's hard to beat Cafe Central in Vienna. Beautiful music every night and really good service.

I second Cafe Central in Vienna. Brilliant!

Almost any cafe in the Piazza Navona on a spring night in Rome. You could be eating dog food and still think you're in heaven.

I haven't been to every cafe in the world so it is impossible to say which is the World's Best.

Riviore in Piazza della Signoria in Florence is by far the best cafe I have gone to- hot chocolate is to die for!

The Cafe Marly at the Louvre gets my vote. Not so much for the food ( although it's not bad) as for the people-watching. When last there, we were seated next to a young model and her poodle, whose hair had been inexplicably dyed green. The woman ordered only olives and champagne, and was still slowly savoring both when we got up to leave two hours later!

Weadles, that is a brilliant travel story!!

Cafe Florian in Piazza San Marco. Best people watching (and pigeon watching) in the world. And the cafe down the street from my house in a rural Italian town...the scorpini are amazing and merlot is only one Euro fifty a glass, which you drink while looking at the mountain.
Ciao
Sia

From my limited experience, I would vote for the Cafe du Monde in New Orleans, Louisiana. Great beignets and coffee!

I love Cafe Luxembourg in Amsterdam. As soon as I sat down I felt right at home!

Cafe de Jaren in Amsterdam.
Love the huge wall of windows looking out onto the Amstel River. I was sitting there having breakfast one morning and some customers arrived via rowboat to the dock in the back - it was special.

Opera Cafe in Barcelona. It was my very first cafe on my very first trip to Europe and I was very taken with the old-time, old-world atmosphere. The beautiful etched-glass portraits of various opera heroines (Brunhilde, Aida, etc.) were lovely.

Of course the Hawelka in Vienna. Try to be there around midnight when Madame Hawelka whips up a batch of her hot raisin rolls.

Cafe Florian in Venice and Cafe Brasiliera in Lisboa. Why? Because I said so, and I have very good taste.

The Cafe Marly in the Louvre is my first choice (surrounded by larger-than-life statues, overlooking the entrance pyramids in the Couer Napoleon - fabulous! - although I have to concur that you don't go for the food or service!), and the Florian in Venice is my second choice (opulent decor, rich in history, overlooking the wonderful Piazza San Marco).

I wish I had some less-well known choices (or that I'd been the first to post them!), but those two are really memorable experiences. I enjoy sitting in almost any cafe, watching the world go by, and have been to many wonderful cafes, but those two remain my favorites.

Bagdad Cafe!

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Deux Magots, "just because"!

The Harbour Bar perched on the quayside in Portrush Northern Ireland. The ullian pipes, the throb of the borhan. Your feet cant keep still. Pints of the black gold and red sails in the sunset.
Heavenly