Songdo Central Park
Inspired by New York City's much larger Central Park, Songdo's Central Park serves as a green oasis from the urban city sprouting up around it. At 101 acres, it is a bit smaller than 1/8th that of New York's, and with far fewer buildings around it.
This was pretty much the only place in the entire city I saw humans out and about. I wouldn't be surprised if more people live in the Chernobyl Exclusion Zone than in this giant new city. But hey, at least the new buildings look nice and less cookie-cutterish than those typically found in Seoul.