The Wolf Popper synagogue was founded by a single man - Mr. Wolf Popper; a 17th century rich banker and trader who lived in Kazimierz.
The synagogue was beautifully decorated, but with Mr. Popper passing it lacked funding. The war further destroyed it, and some parts of the decorations are now to be found in Jerusalem museums.
It ended services as a synagogue in 1965, and was converted into a bookstore selling Hebrew literature as well as beautiful notebooks. Also available are English and other language books on the history of Jews in Poland. A very eccentric little place.
The main feature though to me was the mural on the left when entering the small courtyard; a painting clearly inspired by Chagall with the violin and the fiddler, the bride and groom, the wandering Jew, the menorah etc. Both modern and drawing lines back to key symbols of Hebrew art.
It is a nice place to bring back a little souvenir from Kazimierz. Entrance is of course free!