( CNN ) -- Barmy about bunkers ? Crazy about caves ? From Congress 's former nuclear shelter to the Viet Cong 's tunnels and a Parisian necropolis , here are some of the world 's best subterranean sights . Coober Pedy , South Australia . Tourists wanting to channel their inner Hobbit should head to Coober Pedy . Most of the South Australian town 's 3,000 residents live underground , where they frequent a subterranean church , restaurant , hotel and shops . The town produces 70 % of the world 's opal , and the blazing outback sun is the reason residents most prefer to live underground , as well as working there . Coober Pedy comes from the Aboriginal term `` kupa piti , '' which means `` white man 's hole in the ground . '' Find out more about Coober Pedy on the town 's website . More : More camels than koalas -- 20 Australia discoveries . Wieliczka salt mine , Krakow , Poland . The Wieliczka salt mine , in southern Poland , was worked from the 13th century right up until 2007 . Now a two-mile-long section of Wieliczka -- accounting for only 2 % of the entire length of the mine 's passages -- is open to the public . Things to see include statues , a chapel and a cathedral carved out by miners , all under light cast by chandeliers made from rock salt . Wieliczka salt mine , DaniÅ‚owicza 10 , Wieliczka , Poland ; +48 12 278 73 66 ; tours from $ 11.50 . The Paris Catacombs , France . The catacombs of Paris are ideal for people who like their tourist attractions a little on the dark side . The catacombs contain the remains of more than six million people whose bones were interred here between 1785 and 1860 , when the city 's cemeteries became full . A tour explores one mile of the 180-mile-long maze of tunnels , which lie at a depth of 20 meters . The neatly stacked piles of bones within include the remains of many who lost their heads to the guillotine during the French Revolution . Paris Catacombs ; 1 , Avenue du Colonel Henri Rol-Tanguy , Paris , France ; +33 1 43 22 47 63 ; tours from $ 5.50 . Cappadocia , Turkey . The 200 so-called underground cities of Cappadocia -- dense elaborate networks carved into the soft rock of the Turkish region , capable of sheltering thousands of people -- may have been started as long ago as the 8th century BC . Whoever built them failed to leave their initials on the walls but the Phrygians ( an ancient Indo-European tribe ) may have been responsible , with later expansion by the Persians . It 's known early Christians hid in the man-made caves while they were still being persecuted for their religion . Derinkuyu , extending to a depth of 60 meters , is the largest cave -- it once housed 20,000 people , as well as their livestock . Almost half of Derinkuyu is open to tourists . It 's connected to another subterranean settlement you can explore , Kaymaklli , via an eight-kilometer tunnel . You can find out more about exploring the underground cities at Cappadociaturkey.net . More : How to drink raki : A crash course in Turkey 's signature drink . Mary King 's Close , Edinburgh , Scotland . Mary King 's Close did n't used to be underground -- it was Edinburgh 's busiest street until the plague struck in 1645 . The densely inhabited close was infested badly and a quarantine imposed on the 500 or so people who lived there in a bid to contain the disease . Many of the inhabitants were simply left to die -- hence the stories of hauntings . The close was eventually opened up again and inhabited until 1753 , when the residents were finally evicted to make way for new buildings built above the old street . Mary King 's Close was sealed up for 250 years before being reopened for tours as a vivid snapshot of 18th-century life . Mary King 's Close , 2 Warriston 's Close , The Royal Mile , Edinburgh , Scotland ; +44 845 070 6244 ; tours from $ 11.60 . Seattle Underground , Washington , United States . When the Great Seattle Fire destroyed swathes of the city in 1889 , municipal bosses decided simply to rebuild it one or two stories higher . Built on mudflats , the original settlement had been prone to flooding . Several oceans of concrete later , the new city rose between three and 10 meters above the old . You can still visit the original Seattle , though , on a guided tour . It 's fun to imagine the crowds once bustling along the shop-lined subterranean streets . Seattle Underground , 608 First Avenue , Seattle , Washington , U.S. ; +1 206 682 4646 ; tours from $ 9 . More : Rooms with no view : Underground stays . G-Can flood surge tunnels , Tokyo , Japan . Anyone but claustrophobes should find this vast temple to underground engineering impressive . Begun in 1992 , the tunnels -- 50 meters deep and six kilometers long and growing -- contain pumps and tanks dedicated to keeping Tokyo dry during the rainy season . The highlight is the enormous , temple-like main tank , which contains 78-horsepower pumps and is supported by 59 enormous pillars . Tours of the complex take place three times a day , Tuesday to Friday -- weather permitting , of course . G-Can project , Ryukyukan Showa drainage pump station , Kasukabe , Saitama , Tokyo , Japan ; +44 117 370 9751 ; tours from $ 13 . More : Tokyo travel : 11 things to know before you go . Shanghai Tunnels , Portland , Oregon , United States . The Shanghai Tunnels are a series of passages that connect the basements of many downtown Portland bars and hotels to the waterfront on the Willamette River . Used prior to the 1800s to move goods from the ships that docked here , the tunnels got their name from the belief , probably false , that they were associated with `` shanghaiing '' -- the practice of kidnapping men to serve as sailors . Shanghai Tunnels , Portland , Oregon , U.S. ; daily tours from $ 17 . Greenbrier Bunker , West Virginia , United States . In the late 1950s , the U.S. government asked the owners of the 700-room Greenbrier Hotel , in West Virginia , for permission to build an emergency relocation center -- a bunker -- beneath the property , to house Congress in the event of a nuclear war . Perhaps with some foresight ( it 's now one of West Virginia 's most popular attractions ) , they agreed . The bunker remained fully stocked for 30 years before being decommissioned in the early 1990s . Daily tours of the facility inspect a 25-ton blast door , some of the 18 dormitories , a hospital and decontamination chambers . Greenbrier Bunker , 300 West Main Street , White Sulphur Springs , West Virginia , U.S. ; +1 855 453 4858 ; tours from $ 15 . Cu Chi tunnels , Vietnam . The Cu Chi tunnels were used by the Viet Cong during large parts of the Vietnam War as living quarters , hospitals , supply routes and storage areas -- even a tank was found in one of the tunnels . This 120-kilometer-long complex , part of a much larger network throughout the country , now operates as a war memorial and visitors -- or at least those who can squeeze through the tiny trapdoors -- can explore several of the tunnels . Impress Travel is one company that offers tours of the complex . Moose Jaw , Saskatchewan , Canada . The tunnels built beneath downtown Moose Jaw in the early 1900s were intended to protect Chinese railway workers from persecution during the so-called Yellow Peril , the racist panic whipped up about thousands of Asian immigrants who 'd arrived to find work . Entire immigrant families lived in the tunnels while working above ground , but during Prohibition the tunnels were used for smuggling . Al Capone was among the smugglers believed to have used the tunnels -- daily tours are carried out by an Al Capone look-a-like . Moose Jaw , 18 Main Street North , Saskatchewan , Canada ; +1 306 693 5261 ; tours from C $ 8.50 . City of Caves , Nottingham , UK . Bizarrely , the entrance to Nottingham 's cave network is located in the city 's Broadmarsh Shopping Center -- but that 's a later development . The caves were used as housing from the 11th century until 1845 , when the St. Mary 's Enclosure Act banned the rental of cellars and caves as homes for the poor . Archaeologists are still trying to work out how far some of the caves extend . Visitors to the caves can see medieval wells and cesspits . City of Caves , Broadmarsh Shopping Centre , Nottingham , UK ; +1 115 988 1955 ; tours from $ 8.50 . More : Survival guide to the UK .
In South Korea , a whole town goes underground to escape the heat . Think Seattle 's nice ? Imagine the city beneath it . Drainage systems are dull but Tokyo 's is an engineering genius .