Picture: Davis Staedtler Source: Flickr

1. RESO, Montreal, Quebec, Canada
This complex also know as indoor city is the largest underground complex in the world.
It consists of 32km of tunnels spread over 12 square kilometers and is used by 500.000 people daily.

Picture: Canadian Tourism Commission Source: News Limited

2. Wieliczka Salt Mine, Cracow, Poland (link in Polish)
This mine was built in the 13th century and was continuously operated until 2007 and was until then the oldest operational salt mine. Every year the mine is visited by 1,2  million people that come to see the dozens of statues, three chapels and an entire cathedral.
Picture: Wikipedia
3. Pilseň historical underground, Czech Republic
It is A labyrinth of passageways, cellars and wells built below Pilsen as early as from the 14^th Century.

Picture: LenDog64 Source: Flickr

4. Tunnels of Moose Jaw, Saskatchewan, Canada
It offers two guided theatrical tours about the alleged purpose of the tunnels where you can relive Al Capone’s bootlegging days and experience first-hand the hardships of early Chinese immigrants.

Picture: Matt Boulton Source: Flickr

5. Derinkuyu, Cappadocia, Turkey
An ancient multi-level underground city extending to a depth of approximately 60 m, it was large enough to shelter approximately 20,000 people together with their livestock and food stores. It is the largest excavated underground city in Turkey. It was opened to visitors in 1969 and to date, about half of the underground city is accessible to tourists. (wikipedia)

Picture: Helen Cook Source: Flickr

Picture: Basak Ekinci Source: Flickr

6. PATH, Toronto, Ontario, Canada
According to Guinness World Records, PATH is the largest underground shopping complex with 30 km (19 miles) of shopping arcades. It has 371,600 square metres (4 million square feet) of retail space.

Source: Flickr

7. Shanghai Tunnels, Portland, Oregon, US
The portland underground tunnels are basement buildings with tunnels linking block to block. These catacombs as they were called created a unique network of passages that were over time used for both legal and illegal activities like kidnapping people and selling them into slavery.
8. Underground Atlanta, Georgia, US
Located in the heart of the downtown, Underground Atlanta is one of the city’s favorite attractions and a cultural hub. Opened in 1969 as a “city beneath the streets,” Underground Atlanta still exhibits many of the significant architectural features from its original structure. Visitors can pick up a self-guided History tour brochure at the information booth and discover the history firsthand. Explore six city blocks, 12 acres and three levels of 225,000 square feet of shopping, restaurants and entertainment at Underground Atlanta, a destination with more than 100 years of history.  souce: underground-atlanta

Picture: Faungg’s photo Source: Flickr

9. Dixia Cheng, Beijing, China
It is a bomb shelter underneath Beijing (China) and has now been transformed in a tourist attraction. It comprises a network of tunnels used for military purposes. It has been constructed in 1970s in anticipation of a nuclear war.
10. Setenil de las Bodegas, Spain
This small town (pueblo) is located 157 kilometres (98 mi) northeast of Cadiz. It has a distinctive setting along a narrow river gorge. The town extends along the course of the Rio Trejo with some houses being built into the rock walls of the gorge itself, created by enlarging natural caves or overhangs and adding an external wall. (wikipedia)

Picture: Manuelfloresv Source: Flickr

Picture: Manuelfloresv Source: Flickr

 List put together by news.com.au

+ one bonus underground city:

11. Hackenberg, Veckring, France

 With 1,2 km of underground galleries one of the largest (a gros ouvrage) of the Maginot Line fortifications created between 1929 and 1932 as defense line by the French.

It was a real underground city with alle necessary facilities to accommodate soldiers for a long period of time. An underground railroad connects the different block with each-other.

Even if you visit during summer don’t forget to take something warm to wear!