I am have planned to visit some major universities in the east side this winter.
However, I checked their visit registration, and almost all of them don’t have tour during December 21st-28th.
All I want is just look around campus, see the view, not go into buildings and look for specific stuff.
Is Harvard open for any visitors to just come in and look around?
If you’re not interested in gaining entry to buildings, if you are quiet while there, and you don’t peek into dorm windows, you can walk through the campus at your leisure. The campus is just part of Cambridge. I don’t believe there are further restrictions. I don’t know whether the guided tours of campus run during Christmas week.
Most colleges, including Harvard, are closed during that time. While you can certainly walk around the campus and see Harvard Yard, all the student’s will have gone home as the dorms are closed. In addition, most of the administration will be on vacation as well. About the only staff around will be the maintenance crew.
You asked this same question at Columbia, and the answer is the same. You can walk around pretty much any college campus at any time. Google to see if you can find a walking tour to follow, they are available for most schools (some from the school itself, some maybe created by someone else). The campuses will be quiet, few students around, and most buildings will be locked.