A single Grand Canal photo can tell you so much. A daily delivery of food stuffs arrives, by boat of course, for the waterside market. That boat "parks" between pilings which throughout the city provide specific places for tying up - and remember those pilings came all the way from Scandinavia to form the bottom support for platforms which in turn hold the houses and palaces. Sadly, the viscious tidal waters through the centuries have forced abandonment of the first floors of many of these centuries-old structures and some are even totally empty because of rot.
To understand the uniqueness of Grand Canal architecture, you must realize that these structures were built centuries ago on water-level platforms which, in turn, were constructed on top of 15 foot pilings driven into the marshy land below which was actually sediment that was washed out from the Italian mainland nearby. (And with no assistance from computer-aided design nor cell phone communication among the construction men!) Interestingly enough, much of the wood for pilings came all the way from Scandinavia - by ship of course.
Vaporettos (water buses) run all day long and late into the night up and down the Grand Canal as well as on many other routes in Venice. Note, they run UP and DOWN the Grand Canal. Now if you just want to CROSS from one side of the Grand Canal to the other and you're not near one of the three bridges that span it, don't pay the cost of a vaporetto ticket. Instead, travel as the locals do and use an inexpensive traghetto. It is actually a gondola but plain black and not decorated and please note, you are expected to STAND UP for your short ride ACROSS.