Obsidian Wings, a politically moderate security-focused blog, drifted into the topic of fun business travel and places. It's the comments that make the piece. Many of the comments are about places that would require a time machine to visit.
I can vouch for some of these lost places -- Chiang Mai in 1981, Jerusalem in 1983. I regret not having visited Kashmir when I might have @1981 -- the way the war is going there I won't ever see it. I'm told old Laos was a rare gem. Manhattan in the 1940s and 1950s. Shanghai before the boom. Koh Samui when it was hard to reach.
A time traveler would have no end of wonderful cities and places to visit. Many were most wonderful for a short period of time, modernity has come fast and hard to much of the world. I can't deny the urgency of poverty, but I suspect one day many Chinese will deeply regret what has been destroyed. In my home town of Saint Paul/Minneapolis an awful lot of local history and charm was plowed over for roads and trains from 1950 to 1970.
Travel while you can. You cannot cross the same river twice (or even once).
PS. If once read a book titled '1,000 Places to See Before You Die'. It was awful. Really 1,000 hotels to visit before you die. The author apparently never left her room. I have to admit, I remember some of those hotels fondly -- but really ...