This paradox is easily explained: as already mentioned, the city was built over a relatively short period: founded at the end of the first millennium, it already had all its main structures (“campi” and churches, canals and “calli”, public buildings and homes, palaces and “fonteghi”) by the 13th Century. Then there was no more growth, apart from some "colmata", filling-in the outskirts until expansion in more recent years.
Nevertheless, the city has managed to evolve over the centuries, as every building, church and palace shows signs of transformation over the centuries