The southern seafront was part of the fortification system, originally completed in the second half of the 16th century, until 1868 when Zadar started changing into an open rather than fortified city. New bastion of Saint Nicolas and Saint Francis were built in the western part as well as the Citadel bastion in the eastern part of the preserved medieval walls. The bastion of Saint Mary was built in the middle, in line with the Benedictine Monastery. In the medieval wall there were only two gates facing the sea: Porta Angeli (the Angel's Gate) and the Pusterla Gate. With the construction of the slaughterhouse in front of the Angel's Gate in 1580 a new gate Porta Beccaria was opened, which led to the open green market (Piazza delle Erbe or the Green Square) situated opposite the Bishop's palace.