Mayor Synagogue, Istanbul  Mayor Synagogue is a former synagogue in the Hasköy district of Beyoğlu, Istanbul, Turkey. According to historian , the synagogue was built in the Byzantine era and was called Mayor because it was the largest in the neighborhood. Another historian claims the synagogue was built 300 to 500 years ago by Jews from Majorca. (According to historian , in the 1950s there was a Mayorka Synagogue in Hasköy.) The synagogue building is now used as storage space, workshops, and a billiard parlor. In September 2009, artist Serge Spitzer chose this site for his installation "Molecular Istanbul".