Turn the Colosseum inside out, so that its classic facade faces inward. Make it so that its inner diameter forms a rotunda 200 feet across. Now pave the entire floor in patterns made with mosaic tiles. Let there be tier upon tier of windows and balconies, six courses in all, where the niches would have been. Crown it with a 100-foot-high domed roof untethered by any central support.

And, oh yes, build the whole thing using only the technology available a century ago.

Can't be done?

It already has been, ain the southern Indiana hamlet of West Baden, where the 1902 West Baden Springs Hotel has reopened against all odds.

At its zenith, the hotel was such an architectural marvel, and so exclusive, that tour guides from the Indiana Historical Society say it commanded twice the nightly rate of the Waldorf-Astoria. The cream of Victorian society came for the healing properties of its mineral springs -- and stayed for the illegal gambling that was an open secret in the town -- until the Great Depression put an end to the good times. By the 1990s, the former wonder had become an abandoned shell mired in red tape.

So to stand now in its restored grand rotunda, or atrium, and check into one of the finely furnished rooms that overlook it is to be twice awed: by the restoration's success and by the fact that the structure was ever built to begin with. The experience is equal parts soaring and intimate. I can't think of another space like it, not one that even comes close except perhaps for Rome's Pantheon, which measures 142 feet in diameter and 142 feet floor to ceiling -- and they won't let you spend the night in there.

By day, the 246-room hotel's interior is appointed with natural sunlight filtered through clear panels in the dome. This is the best time to appreciate the harmonic spacing of the Ionic columns that support the rotunda, count the windows and balconies between them, and admire the gold-leaf embellishments. Sculptures and reproduction furniture are arranged for conversation groups, where guests talk to one another in hushed tones. Sound carries surprisingly well in here. The live music that flowed from the atrium's grand piano found me in my room six floors above, even with the balcony doors closed.

By night, a pendant chandelier comes to light. The enormous fixture is round and segmented, much like the massive rosette windows of stained glass in Gothic cathedrals. In fact, suspended from the center of the dome, that's what this multihued light most reminds me of.

The glory days

Behind all the grandeur is a story that starts along the Buffalo Trace in a valley dubbed French Lick.

About a mile down the road from West Baden Springs Hotel stands another hotel, the French Lick Springs Hotel, in the neighboring village of French Lick.

The mineral content of the springs in the valley had people swearing that the waters would cure everything from alcoholism to old age. French Lick Springs Hotel was built in 1840 so folks would have a place to stay while taking the waters. Ten years later, a competitor, the Mile Lick Inn, opened for business on the site where the West Baden now stands.

Rivalries raged. Room rates rampaged. The Mile Lick changed its name. Both hotels were consumed by fire only to be rebuilt more grandly.

The French Lick hotel began bottling the stuff that bubbled from its main spring as Pluto Water. The West Baden answered with Sprudel Water. There was a direct rail line all the way from Chicago, and each hotel had its own station. Local historians say the two hotels, along with numerous ordinary lodgings for average Joes, created a destination so popular that the railroads were delivering more than a dozen passenger cars a day loaded with vacationers.

From the time the domed incarnation of West Baden Springs Hotel went up, though, West Baden was the star. It had extensive gardens, a bank, a stock brokerage, its own opera house, a swimming pavilion called a natatorium, and a double-decker pony and bicycle track.

Its crowning glory was the genius of architect Harrison Albright, who solved the considerable problems of the dome by designing it like an umbrella: sturdy spokes radiating from a center hub, suspending a skin of relatively lightweight materials.

Guides on the Indiana Historic Society's hotel tour say each of the dome's metal ribs rests on something very much like roller skates, hidden behind panels atop each rotunda column. The mechanism, they say, allows the rotunda to bear the weight of the dome while at the same time permitting the dome to expand and contract at a different rate than the building itself. They're actually two different structures that only give the illusion of being attached.

The idea was so solid that even after the hotel sank into obscurity, closed for good in the 1930s and became a Jesuit seminary, found itself turned into a private college later still and eventually sat empty, the dome stayed put.

Before the close of the Roaring '20s, the communities of French Lick and West Baden counted 30 hotels, 15 clubs and, historians say, nearly a score of casinos between them. French Lick Springs Hotel couldn't match West Baden's unique architecture, but the Beaux Arts belle with its long, lazy double porch was elegant in its own right. And it was powered by Thomas Taggart.