In the Netherlands a lot of houses are sitting on wooden poles that stand on sand plates below the surface. The problem we have right now is drought. As long as wood sits below the water it will not rot. But since we had some very dry years the water levels in the ground have gone down and the wood might start to rot and attract fungi.

Even today willow branch mats are still used. They are used primarily for support structures during construction so durability is not always an issue (though of course submerged wood lasts pretty long anyways).

When I visited Amsterdam I saw these ancient looking witch's brooms everywhere- when they clean the streets, it's guys with witch's brooms in front of modern cleaning trucks. I talked to a number of people who said they worked better than the modern style (and indeed, watching the cleaners do their job, it was clear the witch's broom excelled at reaching into tiny corners and pulling out things before the truck came through).

There's lots of wood under Manhattan and Philadelphia, too.