Free Roller Wave event (NYC)
Friday, March 12th from 5pm to 9pm at Lincoln Terrace Park. I can vouch for the surface. It's fairly smooth concrete most of it is painted. The area is fairly large and music should be good (based on my past experiences with Roller Wave events). If it's not perfectly flat if that's a deal breaker for you.
https://mailchi.mp/aedbc59df416/roller-wave-out-door-skates-disco?e=29f2dc94f9