While in Stockholm last month, I visited the Skogskyrkogården cemetery and, while a beautiful cemetery with rolling hills, towering trees, wildflowers, and interesting architecture, I did not quite understand what made it so special as to "make the cut" for this highly selective list.
Conversely, while in Mexico in 2018 or 19, I was absolutely blown away by the Xochicalco archeological site in Morelos state. It was a reasonably easy day trip from CDMX - bus to a small town 90 minutes away, then a 10 min taxi ride, yet I had the entire site and museum entirely to myself until the very end of my visit 2 hours later.
I even took a nap in the grass next to the feathered serpent pyramid, it was eerie.
And we're not talking about a small site: there were multiple levels, ball courts, former residential quarters, etc.