Watch as we construct a secret underwater house with a hidden underground passage using only primitive tools and natural ...

Researchers explore the possibility of a secret passage that may have been used in ancient times for strategic, diplomatic, or commercial purposes.

searching for tunnels that ran through it like hidden passages in the ceiling of a mansion. Local porters ferry the expedition team’s equipment across an underground river to reach various ...

The Slave Haven Underground Railroad Museum ... The 19th-century home is filled with secret passages and trap doors that were used by runaway slaves attempting to flee north to freedom.