"There is a vineyard in Paris itself - in Monmartre!"

Yes, but it's not going to be any prettier than any vineyard in the countryside in early March.

I wonder if there is a special Montmartre wine but yes vineyard is very tiny.

I believe the vines are Clos de Montmartre, a red wine not considered much of anything special. The mairie there sells them and the earnings go to pay for social services in the arrondissement. There are at leasst three other vineyards in Paris, one in Belleville - I forget the others. They are all tiny.

Still vin DOC Paris could be collector's item for bottles? Suppose however there is no DOC.