There have been plans/proposals to refill the aquifer under Venice [1].

The construction of the Modulo Sperimentale Elettromeccanico (or MOSE) that is meant to be raised in times of high water started back in 2003 [2].

[1] http://www.geotimes.org/mar04/geophen.html

[2] http://en.wikipedia.org/wiki/MOSE_Project

Venice is built largely on wood pylons. They are in many cases over a thousand years old.

Nevermind Venice, which is at least still above sea level (barely)---what about New Orleans?