12. Sydney Harbour, Australia
Sydney has two spectacular city icons, and they share the same fabulous harbor. The Opera House may be the one with the fancier lines --- its "sails" were designed to resemble the boats that sail past the building --- but it doesn't dwarf the magnificent Harbour Bridge.
A great place to view both of these landmarks is Circular Quay, from where ferries go back and forth to the North Shore. You can gaze comfortably on one of the world's most unforgettable maritime skylines from the patio of Peter Doyle's, a spectacular fish-and-chip-cum-sushi restaurant on the quay; sydney.com; doyleatthequay.com.au
13. Inside the Thrihnukagigur volcano, Iceland
Iceland is a spectacular living wilderness, and in summer it's possible to journey right into the inner cavity of the Thrihnukagigur volcano, which has been dormant for 4,000 years.
After a short hike across lava fields, participants descend 120 meters via a cable car into the heart of the volcano and its magma chamber, only accessible between mid-June and the end of July.
Discover the World offers three nights in Iceland including accommodation, volcano visit and a look at other natural wonders as well as the capital, Reykjavik, from around US$1,130; discover-the-world.co.uk
14. Monument Valley, United States
You'd be forgiven for thinking this thrilling red rock vista at the conjunction of Arizona and Utah was a movie set. But although it's served as the backdrop for many John Ford movies, this corner of the Navajo Nation is for real.
The best way to experience the area is to stay overnight, then ride into the park with a Native American guide who can arrange a visit with some of the residents. Particularly magical is a nighttime visit around the time of the full moon.
General admission US$5; navajonationparks.org
15. Taj Mahal, India
It may be the most clichéd image in the world, but visitors still gasp the moment they first set eyes on the world's most famous shrine to love.
Best enjoyed at sunset, when there are not too many tourists around to spoil the spell, or over a drink from a distance at Amarvilas, a luxury hotel overlooking the magnificent white marble mausoleum.
Built by Shah Jehan in the 17th century in memory of his third wife Mumtaz, the Taj Mahal forms part of the Golden Triangle, which is the classic first tour for visitors new to India.
Intrepid Travel offers seven days from Delhi, taking in the pink city of Jaipur as well as the Taj Mahal, from US$805; intrepidtravel.com
16. Kasanka bat migration, Zambia
Five million bats cluster together in one tiny corner of Zambia's Kasanka National Park every November.
Orange-brown in color, they feed off the swamp forest's delicious wild fruits, on which they chomp solidly every night (making sunset and dawn the best times to view them). After the bats abandon it, Kasanka is spectacular in a different way: all that remains of Bat Central are stripped, broken trees and an eerie silence.
Naturetrek has a Swamps & South Luangwa Zambia safari departing on November 4, taking in the bat migration. US$2,725 includes all transport, full board accommodation, park fees and guides; naturetrek.co.uk
17. Carlsbad Cavern, New Mexico, United States
Although Carlsbad also has a colony of bats that fly out at dusk when the cavern is closed, they can't equal the utter spectacle within.
Some 230 meters beneath a stand of cactus-studded rocky slopes in New Mexico lies a wonderland of 117 caves formed when sulfuric acid dissolved the surrounding limestone.
Allow a couple of hours to marvel at the eerily-lit stalactites, stalagmites and other rock formations as you wander through these amazing subterranean halls.
It's like being in Hans Anderson's "Snow Queen," the fairy-tale set in a mysterious ice palace --- but this one is just comfortably cool and not slippery. There's even an elevator for the 79-story ride back to the surface; nps.gov/cave/index.htm