I'm writing a story in the genre of Heroes, The 4400 etc in which a group of apparently random civilians, mostly US citizens, are subjected to some alien influence and gain strange powers, whereupon the government wants to keep an eye on them and run tests to find out exactly what they can do. The DHS has stepped in and invited several of them to come to a facility where tests can be run (probably experts from the NIH will be invited in for this), and where one of the characters who needs unusual medical assistance can receive it.
I'm looking for an actual location, based on the following criteria:
The characters are not being held prisoner against their will. (Rationale: making people with superpowers, angry or panicked, is a very bad idea. Much safer to let them think they're free, and just keep an eye on them.)
The whole thing is supposed to be secret. (The people in charge, would prefer other governments not find out about this at least for the moment. Whether the attempt to keep it secret will actually succeed for long, is a different question.)
Preferably on or near the east coast, ideally within reasonable commuting distance of Boston.
What would be a suitable location?