A short excerpt from the WIKI page on The History of hidden passages:
Secret passages, also commonly referred to as hidden passages or secret tunnels, are hidden routes used for stealthy travel, escape, or movement of people and goods. Such passageways are sometimes inside buildings leading to secret rooms. Others allow occupants to enter or exit buildings without being seen. Hidden passages and secret rooms have been built in castles and houses owned by heads of state, wealthy individuals and criminals. These passages have helped besieged rulers to escape from their attackers, including Pope Alexander VI in 1494, Pope Clement VII in 1527 and Marie Antoinette in 1789. Passages and tunnels have been used by criminals, armies (notably the Viet Cong in the Vietnam War) and political organizations to smuggle goods and people or conceal their activities.