47. Going under...
When this bricked-up doorway was first built, it would have been the main street (canal) entrance to this residential building. Visitors would step out of their gondola onto the now completely submerged stairway up to the entrance, the bottom of which would have been some way above the high water mark.
The day this picture was taken, the water level was exceptionally low, or we would not even be able to see the entrance steps at all, and yet it still only just reveals the bottom of the doorway. Clearly, the high water mark today is probably a fair bit more than a metre above where it was when this building was constructed. The water level could not have risen anything like that much, so the building has definitely sunk.
Now the doorway is a doorway no more. The lower level of this house is now a very wet basement, and the entrance is via a newer walkway which bridges from what has become the new front door down to the opposite side of the canal.
In most other places in the world, this would be a natural disaster, an argument with an insurance company, and a redevelopment plan. Here it is a shrug of the shoulders, an alternate practical solution, and a willingness to accept that, over time, everything changes.