The Bach quadrangle encompasses the south polar part of Mercury poleward of latitude 65° S. It is named after the prominent crater Bach within the quadrangle, which is in turn named after Baroque composer Johann Sebastian Bach. The quadrangle is now called H-15. Adjacent quadrangles to the north of Bach are Discovery quadrangle (0° to 90° W), Michelangelo quadrangle (90° to 180° W), Neruda quadrangle (180° to 270° W), and Debussy quadrangle (270° to 0° W). It is opposite the Borealis quadrangle at the north pole.