Last weekend, on a trip to Tennessee, I visited Great Smoky Mountains National Park, a World Heritage Site. This was the 62nd World Heritage Site I've visited.
I couldn't tell at the time what made this more special than other National Parks and thus worthy of being a World Heritage Site. It turns out it's the biodiversity, so it makes sense that doesn't jump out at me. (Though I did see some nice trees.)
This is the first site I've visited since I was in Brussels almost two years ago. None of the sites inscribed in 2016 or 2017 were ones I had already visited, so my percentage has dipped from the all-time high of 5.92% sites visited in 2015 to 5.78%.