7 Underground Wonders of the World

1. Miles and miles of tunnels and caves under Castle Hill in Budapest, Hungary.

2. Miles and miles of tunnels and caves under Castle Hill in Budapest, Hungary.

3. Underground town in Coober Pedy, Australia.

4. Catacombs under the chapel on site at the West Norwood Cemetery in London, England.

5. Catacombs under the chapel on site at the West Norwood Cemetery in London, England.

6. Tunnels under Moscow, Russia.

7. Tunnels under Moscow, Russia.

8. Caves and mines throughout the Ozark Mountain Range in the Midwest.

9. Caves and mines throughout the Ozark Mountain Range in the Midwest.

10. Networks of catacombs, quarries and other tunnels running under Paris; some were used by the French Police in the 18th Century.

11. Networks of catacombs, quarries and other tunnels running under Paris; some were used by the French Police in the 18th Century.