It is difficult to say as each person is diffrent and will take away somthing diffrent from each experiance. The best experiances that help broaden ones mind are the ones that make the person think about life from anothers perspective.
a few examples might be to visit the time around the tearing down of the berlin wall. 
or maybe a visit to the concentration camps in germany. 

Although these are locations durring difficult times they are likely help someone experiance the hardships of others.
But what each person takes from an experiance is highly subjective.
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence