A Remaining Bridge - Morphological Tourism

Ponte di Rialto

 History:
- The bustling market present in Rialto was marked by its entrance, a bridge painted by Carpaccio, which was replaced by a stone arch in the late 15th century. The first streets of Venice were made of dirt and garbage, people threw their trash out of their windows. These unreliable streets
were not usable during the frequent high tides and damp weather.  Most people went out on horses, so bridges in Venice were originally built without steps. The garbage amounted to massive quantities, so pigs openly roamed the street to control the trash.  To solve the problem of clean water, rainwater was gathered
by the pilele, white stone stripes that run along the walls of the city. Rain was  also collected in wells dug into the sandbanks of Venice and subterranean cisterns. When rain water was not enough, Venetians collected water from the Brenta River.
>> http://people.umass.edu/latour/Italy/VeniceUrbanHistory/


Questions:
-Which was firsts of the islands to become part of the Venice we know today?
-Has land been redistributed from the surrounding area to fill up the more important center of the islands? Or, has that land been lost to flooding?

Hypothesis:
-There only seems to be one bridge in the map from the year 1150 which is called Ponte di Rialto across the Canal Grande. I suspect that it has been an anchor point in the past and the present.