Dag Hammarskjold Public Plaza

It is open from 7:00am to sunset. The sign reads as follows.
This plaza is open to the public
This plazza is accessible to the physically disabled. To ensure compliance with requirements regarding this urban plaza, a bond has been posted with the comptroller of the city of New York. This Plaza is owned and maintained by Dag Hammarskjold Tower Condominium, 240 East 47 Street, New York, New York 10017.

Amenities
Seating Required ---------193 Linear Feet
Seating Provided ---------241 Linear Feet
Trees Required -----------9
Trees Provided -----------23
Bicycle Parking------------12 Spaces
Planting Required---------900 Sqare Feet
Planting Provided---------25000 Square Feet
Drinking Fountain --------1

It has a dedicated website too.