Up to 30 people can sleep over at the remote UFO-like dome, Integratron (integratron.com), in the Mojave Desert near Palm Springs, California.
Twenty glass igloos are the star attraction at the Igloo Village (kakslauttanen.fi), in the woods near Saariselka. There are snow igloos, log cabins and a Finnish peat house to stay in, too.
Twenty seven of the ancient cave dwellings that pock the fairy chimneys of Cappadocia have been styled for the modern-day troglodyte traveller at Yunak Evleri (yunak.com).
4. New Zealand
A Bristol B-170 dating from the 1940s offers an unusual bed for the night at The Plane Motel (woodlynpark.co.nz) on New Zealand's North Island.
A wine barrel is just the place for an old soak to hole-up for the night. Head for Hotel Lindenwirt (www.lindenwirt.com) in Rüdesheim, where there are six two-bed barrels up for grabs.
At Utter Inn (mikaelgen berg.com), you'll find your lodgings in the middle of a lake near Stockholm. By day, you can take a running jump straight off your dock for some lake swimming. By night, you sleep below the water's surface with the fishes.
7. The Netherlands
Floating in a canal in The Hague, The Capsule Hotel (capsulehotel.info) offers quirky accommodation in two pods that were once used as rescue vessels for oil-rig workers.
Two houses shaped as shells provide a home from home at Casa Caracol (mayaneyes.com) on Isla Mujeres off Cancun.
A night in the cells is a matter of choice for today's visitors to the Jailhotel Lowengraben (jailhotel.com), in the old town of Lucerne.
A gypsy wagon at Les Roulottes (lesroulottes.com) provides a getaway for the romantically inclined in Beaujolais.
For more unusual hotels, get 'Bed in a Tree' by Bettina Kowalewski (Dorling Kindersley, £14.99).