In the next millennium, even Central Asia, about as remote as you can get now, will likely be well trodden. Finding an unusual, or even uncrowded, destination will be hard. The last frontiers will be gone, the undiscovered country will not exist. As air fares fall, roads are built, countries open up and the world’s middle class multiplies, tourism will be one of the great growth industries of the next century. ““As long as there’s peace and prosperity, people will travel,’’ promises Karen Cure of the Fodor’s guides.

Already, travel experts are trying to spot the in spots of the future. ““I’ve been hearing great things about Vilnius [capital of Lithuania],’’ says Jake Brooks, the publishing director of the Let’s Go guides. But not just any place will do. As leisure time dwindles, it becomes more precious. Future travelers will increasingly expect excellent service, beautiful facilities and lots of comfort, says Wendy Perrin, author of ““Wendy Perrin’s Secrets Every Smart Traveler Should Know.’’ ““People want to be pampered,’’ she says. Airports all over the world are starting major renovations. Spas and hotels will keep on booming. ““Luxury will be in; service will be in,’’ says Bill Fischer, travel agent to the stars. Some people are even staying in hotels in their own city, just to escape. Getting away without going away will only get easier as techno-savvy entrepreneurs build more places like Japan’s Phoenix Seagaia, an enormous complex where you can ski and surf indoors.

Still, virtual reality will never be able to replace the feeling of real sand in your bathing suit, and relaxation may not be enough for the overworked Yuppie of the future. Already, extreme or ““adventure’’ vacationing is popular among baby boomers. ““They’re looking for trips that pack a lot in a short period of time,’’ says Perrin. ““It’s not enough to relax and get a tan, but you have to explore the culture, lose weight and rekindle your relationship, all in three days.’’ Outward Bound on the moon?

And then there are the ““dependables,’’ as travel researcher Stan Plog calls the people least likely to be in Kashgar in 2020 and most likely to be at Disney World right now. For them, a bit of artificiality may be the best policy. ““Real’’ destinations, like bawdy Key West, aren’t as family-friendly or cheap as, say, Key West World–Orlando’s sanitized, EPCOT-like re-creation of the actual town.

The millennium itself is bringing still more of these places. Britain is planning to erect a monster Ferris wheel, the Millennium Wheel, that will literally cast a shadow over Parliament. A 25-minute ride into the sky will afford families spectacular views of London and the surrounding area. Millions will spin. Says Nick Hanna, the editor of the forthcoming ““Rough Guide to the Millennium’’: ““It’s completely pointless, but what a fantastic idea!’’ Like a virtual Kashgar in Las Vegas in 2050.