83. Normal working conditions.

Near the right hand edge of the image of Ca' Dario posted here on August 10, you will see what looks like a 'No Entry' sign. You would probably think that despite what I had said on another occasion about the apparent lack of traffic restrictions on the waterways of Venice, that this meant the Rio (canal) next to the palazzo was one-way traffic only. You would be wrong. It is indeed a No Entry sign, but the words underneath (which are clearly visible in the original image) in fact say "Rio Chiuso Per Lavori" – Road Closed For Works.

This is the sort of works that make a Rio in Venice impassable. In Venice, you can't repair one side of the street, leaving the other one open. In Venice, it's all or nothing, you have to close the whole street - and then take the street away before you can start work. It is never the 'street' itself that's the problem, it's the sides of the road, the foundations of the buildings, that need the periodic attention.

In many parts of the world, if it rains enough to be soggy underfoot, building work stops. If that was the union rule in Venice, work would never start. What passes for normal building conditions here would trigger a walkout almost anywhere else in the world. Here it is always soggy underfoot, damp where you're trying to work, and smelly all round – especially this close to the canal-bottom sludge in summer.

Most of the buildings in Venice are brick, a porous material, but this picture reveals the secret of what makes building out of brick possible. On top of the wooden pilings that create a more stable floor, the foundations of most of the buildings are constructed from Istrian stone, chosen not just for its strength or for its easy availability, but because it is completely non-porous, creating a moistureproof barrier between the watery streets below and the brick buildings above.

Caissons, which seem to be made from steel and concrete, are lowered into place to seal each end of the section of canal that needs to be repaired, and then the water is pumped out. The seal is never perfect, so all the time workers are inside the drained area, pumps are keeping seepage from the lagoon at bay.

Spare a thought for the original builders of the wonderful - amazingly wonderful - buildings that were erected five hundred or even a thousand years ago in the middle of this tidal lagoon under the most adverse building conditions imaginable, without electric pumps or power tools, or any of the benefits of all the other modern technologies we take for granted.

I don't know about you, but I take my hat off to them in admiration.