There are few places in the world I would classify as a place that literally everyone in the world should visit. Hiroshima's Peace Memorial Museum and Park would be one of them. Before visiting Hiroshima, I admit I was not all "about" going there. I realized it was an incredible tragedy, but the weight of it was not there. I hate to sound callous, but I'm being honest.
That's why I believe this is something everyone should see. I could classify myself as passionately anti-nuke. My personal favorite display at the museum was the great wall of all the letters the mayors of Hiroshima have written to leaders all over the world about the nuclear programs. He urges them in a peaceful manner to consider their dire history.
I won't spoil any of the exhibits, but it's an emotionally exhausting visit. Try not to rush through as there is a lot to learn and absorb. Hiroshima is second to Kyoto as my favorite city in Japan. It has a unique personality, and just being in a city that was completely devastated but has bounced back 110% ... it is an honor. Please go to Hiroshima and you will feel connected to all of humanity.