Sicil ---- The whole of the Greenway is a civic (civitas) or public (pulicus) space in that you don't need to have the bucks for S&W you can go to DD or MacD or truck, cart or even bring it from home and then walk and eat on the Greenway -- anyone can do thatHands down, Atlantic Wharf.
....And finally, contrary to BRA's public statements during its "planning" gyrations, not a single civic space (opera, black box theater, performance space) was sited along the edge of the Fort Point Channel from Atlantic Wharf, Intercontinental, Independence Wharf)
While not strictly Public - the New England Aquarium is certainly a civic venue and it is certainly essentially located along the Greenway
But more substantively -- I sincerely doubt that when Olmstead designed the Fens back in 1879 that he imagined the institutions (MFA, Gardner, SMFA, Mass College of Art, etc) which would cluster along his Fens -- originally designed as a waste water and flood control project
Let's come back to this matter after the Greenway has been in existence for few dozen years -- we'll almost certainly see some additional civic / public function situated near / on the Greenway