My only personal experience with "safe places" is in "safe place imagery" which is a very cool visualization technique used for relaxation, meditation, and even in therapy along with amazing tricks like EMDR for helping to manage or eliminate triggers and "zero out" extremely stressful memories.

Quite as it should be, the best "safe place" is the one we create for ourselves in our mind. I never imagined students would demand a real-world physical equivalent that somehow everyone else in the room is supposed to comply with.