NEW YORK (Fortune) -- What more is there to say about megayachts? They are status symbols, objects of luxury that would make Marie Antoinette blush, perfect for hiding from prying paparazzi or niggling underlings for months at a time.

Not too long ago, a 100-foot yacht with a nice kitchen would have been quite a prize. Nowadays, if you don't have a 600-bottle wine cellar, or a helipad, or a hair salon, or three Jacuzzis, or a couple of grand pianos, you might as well be rowing around in a canoe.

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Yet while megayachts might seem like frivolous opulence, they are also feats of naval engineering. Their owners are right to be proud, as these ships are often entirely hand-built by hundreds of artisans crafting the hull, molding the cabinetry and designing high-tech gizmos.

"They are truly amazingly engineered," says Diane M. Byrne, an editor at Power & Motoryacht who compiles an annual list of the biggest motor yachts, which informed much of our list. "They are art forms, too."

Here, we look at 10 of the finest yachts in the world, both motorized and sailing. They are the 10 longest yachts owned by Americans, presented in order of length from bow to stern.

For further browsing, check out Power & Motoryacht's 2005 list and Yachtspotter.com.

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