MIT Lincoln Labs is funded by the department of defense. They do a lot of classified work, and may have large areas that are off-limits to non-US citizens. I

MIT Lincoln Labs is funded by the department of defense. They do a lot of classified work, and may have large areas that are off-limits to non-US citizens. I had a Summer internship at a similar institution, where my work wasn't classified, but was sensitive enough and close enough to classified work that only US citizens were allowed past the keypad lock to my desk area.