For thousands of years the marshes, swamps and low-lying islands of the lagoons at the extreme north of the Adriatic were real-estate that no one wanted. True, the Romans built the port town of Grado on a tiny island, but that was to support Aquileia, their garrison about ten miles inland. Aquileia was a crucial checkpoint controlling the traffic leaving the Italian peninsula to the northeast and, more importantly, a bulwark against potentially dangerous traffic dressed in bear-skins trying to get into Italy.
Interest in the seemingly worthless bits and pieces of the northern lagoons was awakened, however, when the western Roman empire collapsed. It happened with alacrity — only a slightly dyslexic variation of the name of the first great barbarian invader, Alaric, who came pillaging in the year 401. Two years later, the Visigoths swarmed in, and a few decades later came the mother of all invasion metaphors, Attila the Hun. Then — we’re not nearly finished — came Theodoric the Ostrogoth in 489 and another wave of generic-brand Goths in 493. Finally, the last great invasion, that of the Longobards swept through the same territory in 568. By this time, as you might well imagine, farmers, fishermen, housewives — heck, even roughnecks who enjoyed a good fight once in a while — living along the main invasion route near the coast decided to move away. Some went west into the mountains and founded a series of hilltop communities that still exist today. Others turned east, bringing their survivor vitality to land which no one else wanted. Thus did a series of remarkable island cultures spring up in the lagoons; people simply trying to get out of the way and be left alone moved out into the marshes and log by log, brick by brick over the centuries painstakingly put together towns with names like Chioggia, Caorle and Venice.
The Venice lagoon is almost at the top of the Adriatic about 100 km across from the Istrian peninsula of Croatia. It is an enclosed bay spread across more the 100 islands of varying size, many of them linked by bridged and canals. The modern metropolitan city of Venice is across the train trestle (upper left of the image) on the mainland. The island "everyone knows" is this image. It is the historic center and is about halfway up the lagoon. The red dot marks the entrance to the Grand Canal (above the dot) directly in from the entrance from the Adriatic (lower right). This image spans about 6km/4 mi from side to side.
Venice, of course, did not just survive; it thrived, ultimately becoming la Serenissima, the Most Serene. Indeed, it is difficult to look at this unique waterborne jewel, this kaleidoscope of canals, bridges, spires, homes, princely palaces and museums, this great Medieval maritime republic, Crusader and China-explorer, this splendid bastion of art, architecture and music, at once a modern city and yet a reliquary of 1000 years of glory —difficult to look at it and think that it all started out as a bunch of refugees in mud hovels. One thinks: If Venice, why not Mars? It couldn’t be much harder.
Venice over the centuries, to say the least, overshadowed her sister settlements in the lagoons; nevertheless, a few of them, too, are worth seeing. Directly to the south of Venice and closing the Venetian lagoon is Chioggia, a town which had its own independent existence for centuries until it fell under the dominion of its powerful neighbor. It then served as a defensive bulwark for the lagoon, bearing the brunt of invaders from the sea trying to get at Venice, itself. Modern times has seen the economy of the island taken over almost completely by commercial fishing. Motorized traffic now buzzes around the streets as Chioggia has been connected to the mainland by a bridge since 1921. The physical layout of Chioggia is quite simple. There are three canals crossed by a number of small streets. There is one main boulevard. The island is accessible directly by car from the southern end of the lagoon or by bus and ferry from Lido, the northernmost of the three islands in the lagoon. Although there is by now a tourist trade in Chioggia, there are lots of sturdy fishing craft plying the waters — and there is not a single festooned gondola. Chioggia is clearly a working-class neighborhood.North of Venice is the small town of Caorle, originally called Caprulae by the settlers who fled the Longobards to found it in the sixth century. Over its long history it has been dominated by Venice, sacked by Trieste and Genoa, and, in general, not had a particularly significant history. Yet, it is notable today for its Cathedral from the eleventh century. Even farther north, at the very top of the Adriatic, is Grado, itself, which became even more important than it had been as a harbor for Aquileia; it prospered as a haven for those from Aquilea fleeing the invaders. The religious history, too, of Grado is fascinating in that it was an important center of the early Christian faith. The Basilica of Santa Eufemia, stemming from the sixth century, is a notable example of a paleo-Christian church, and the town was the focal point of an early schism between Rome and Constantinople in the seventh century. Grado is today an orderly array of symmetrical little blocks housing its modern population of about 10,000. If you are in that area, then the town of Aquilea, too, is a must. It has extensive Roman ruins, attesting to its importance as one of the largest cities in the Roman empire and gateway between east and west within that empire.
2. added Nov. 2, 2018 -- on the MOSE project to save the lagoon and city from flooding.