WARNING: This story contains the descriptions of off limits places where people are not allowed to go. Listen, but watch your step. Things could get dangerous.

For even the most seasoned travelers—the ones who have been to every state and every continent—there are still places that for whatever reason—be they geographical, political, or even for your own personal safety—you just can’t visit.

We're taking you all the way from Snake Island in Brazil to the Vatican Archives to find out what makes these places off limits. Lonely Planet destinations editor Ben Buckner joins in to explain his favorite places no one is allowed to go, and aerospace historian Peter Merlin even discusses the mystery site of Area 51.

Show notes are on Ripleys.com. You can join the Notcast conversation on Twitter or drop us a line at [email protected].