The lowest point in western Europe is 6.74 meters below sea level and falling. It lies in a boggy area of decomposing peat outside the cheese mecca of Gouda, the Netherlands, and is identified by a seven-meter marker plunked into a brackish pool at the entrance to the Van Vliet truck dealership. (The dealership's owner erected the marker, taking a little license with the facts; the actual low spot is a few hundred meters away.) The Fodor's travel guide does not mention this corner of ­Holland, but it's a focal point for the question of how to plan for the risks and realities of climate change.

That's because the town of Gouda is considering whether to erect 4,000 houses--some of which might float--just two kilometers from this continental nadir. Subdivisions may rise on portions of the sparsely developed farmland near the truck dealership, a 50-square-kilometer area surrounded by dikes and a canal. Such reclaimed lowlands are called polders; they're kept dry by pump houses that suck away rainwater and ground­water seepage. The Dutch have always built on polders, but doing so now, as flood risks rise across the country, will require new approaches that could get an early test in this particularly low region, called the southwest polder or Zuidplaspolder. "It sounds, sometimes, somewhat illogical," concedes Marco van Steekelenburg, an urban planner with the regional province of South Holland, who took me to the site. "But that is what we have to investigate: how illogical it is. We have been given a challenge: can we find solutions which are climate-proof?"