Mr. Samton, on the bay side of Fire Island, had to drive his pilings 12 feet deep.

Not the least of his triumphs, she said, was the engineering artistry that situated the building atop deep pilings at its waterlogged site.

For concrete and steel buildings set on deep pilings, with lower floors used only for parking, insurance rates have generally doubled or tripled at the Alabama beaches.

Installing deeper pilings "wouldn't have cost a lot of money," Mr. Roussel said.

In order to support the building with much of its foundations underpinned by this tunnel, engineers had to drive concrete pilings 26 feet deep.

A new foundation with deep pilings would be laid and the original buildings reassembled on top of it, allowing for much needed expansion and modernisation.

Like builders there before him, Mr. Massaua put his foundations on those deep pilings.

Generally, deep pilings or foundations must be driven into solid soil (typically hard mud or sand) or to underlying bedrock.

For a building of real height to be stable on this site, it would need impossibly deep pilings.

Piers sit atop pile caps on wooden pilings approximately 70 feet deep.