Sierra Madre, not exactly a secret place
Honest Hearts, Zion National Park
Lonesome Road, Unknown, likely the grand canyon or some other desert valley.
But Old World Blues is an interesting thought. Unless the Big Empty is underneath some big huge city or US famous place, how can a snowglobe for the Big Empty be logically put out there? I mean, it was a top secret research facility. How can it be presented in such a way it doesnt countermand the secrecy of The Big Empty? (Unless that under a huge city/park bit is what happens)
