Paris Markets

It's probably the Marche des Enfants Rouges. It is partly covered, but outdoors. It's a fine place to get a snack or lunch these days, but can be crowded. A bit more than five blocks away (that notion isn't helpful in Paris), but still in the vicinity. I wouldn't call it "large" either, but it's big enough to be varied.

Possibly Marche d’Aligre, but it’s more than five blocks.

Yeah, Marche d’Aligre is pretty far from the Pompidou. It is likely Marché des Enfants Rouges as it is about a 15 minute walk from there. And, if you google “oldest outdoor market in Paris” that is what comes up.

thanks , it isn't the the rouges enfants market, still trying to find this !

Your mention of "shopping" makes me think of Les Halles, partly a great open air market and partly an elegant glass and iron structure by Baltard in central Paris before the market was moved to Rungis in the 1970s. The much beloved structure was torn down and replaced by a huge shopping center of a few incarnations all of which seem to be disliked.. See if this link will help you. There's a vibrant painting of the former market in the Petit Palais.

https://en.wikipedia.org/wiki/Les_Halles

Oh, if it's les Halles, don't bother. You'll probably pass by anyway: nowadays it's a modern shopping mall devoid of anything historical.

“thanks , it isn't the the rouges enfants market, still trying to find this !”

Can you provide more information? Is this someplace you’ve been before and can describe...?

As others have said, maybe you mean Les Halles. The history of what it once was might be why you’re referring to it as one of the oldest markets. But it is more of a mall than outside.