The Da Ponte Fountain dates from 1666, replacing an older one on the same site. Its superstructure is in the shape of a bridge, surmounting an octagonal water basin surrounded by fifteen pilasters, each bearing the arms of local noble families who had contributed funds toward the fountain.
A subaquatic aqueduct connected the island of Koper to the mainland as early as the end of the 14th century. By the 16th century, the 10,000 inhabitants of the city were facing a water shortage, rainwater cisterns having become inadequate. In the 17th century, Niccolò Manzuoli recorded the city water supply, noting that a 2-mile distant spring at Colonna was piped to the island via wooden underwater tubes, some of which have been unearthed during excavations by modern archeologists.
The water spurts from four mascarons at the base of the arch. The fountain was used as a source of potable water until 1898.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.