While during most of the 16th c. vocal polyphonic music had steadily focused on a four-part structure, around the 1570s the number of parts underwent a remarkable increase, particularly in sacred music, all over Italy. A typical example is the Concerti by Giovanni Gabrieli, published 1587, and one of the cornerstone works of the second half of the 16th c. The structure of these pieces is not particularly complex. Their appeal consists chiefly in the pursuit of grandeur, the dynamic play of choral masses, the restless rhythm of the chord sequences and the search for a sound rich in harmonics.