Isaac's Synagogue was named after its founder, Izaak Jakubowicz (reb Ajzyk reb Jekeles). One of the most famous Hasidic legends is connected with this pious Jew, who lived in Kazimierz.
One day he had a dream about a treasure hidden in Prague, near the Charles Bridge. Without thinking twice, Isaac went to Prague and found the bridge he had seen in his dream. The bridge was filled with soldiers, and Isaac was unsure what to do next when one of the soldiers approached him and asked what he was doing there. When Isaac told the soldier about his dream, the man laughed: "Only a naive fool would come so far for a dream! I myself keep having this dream that in a house of a Krakovian Jew named Isaac, son of Jacob, there is a treasure hidden under the furnace, but I'm not so foolish as to go to Kraków and check it out. After all, every second Jew is named Isaac, and every third, Jacob!" Isaac thanked him, returned home, dismantled the furnace, and found a great treasure, becoming one of the wealthiest citizens of Kazimierz—wealthy enough to found a magnificent synagogue.
Today the early baroque building with a beautiful, stucco-decorated vault and marvelous arcades in the women's gallery houses an exhibition on the history of Polish Jews.