The Venetian Jewish Ghetto (incidentally, the word “ghetto” is derived from the Italian, gheto) was the first to be instituted, in 1615. The main square is composed on three sides by some of the tallest structures in Venice, owing to the population density and restricted building space.
Synagogues were built into existing buildings, not only to conserve space but because under the Venetian Republic, synagogues were not permitted to be freestanding structures.
One of the four synagogues, the Levantine Synagogue (on the left).
Ornamentation on the entry to a Yeshiva. 
In November 1943 Jews were declared “enemy aliens,” and over 200 were rounded up by summer 1944, with most being deported to Auschwitz-Birkenau.  In the main square there are memorials.

Venice’s Jewish quarter is small in population, with more tourists than Jewish residents.