OP - great advice on this thread. Isabella Stewart Gardner museum is lovely, and we like Legal Seafood and Mike’s Pastry in the North End for cannoli.
As the mother of a college aged boy I have to disagree with a few of the well-intentioned suggestions you’ve gotten .
While Boston is a place with fine museums and historical sites these are not the places I’d take a high school boy. Lexington and Concord are pretty towns and would be a nice place for a family brunch or for a nice walk when visiting a kid attending a Boston college, but they are not places where your son will hang out, and unless he’s a history buff or rabid Thoreau fan he’d likely find them boringly suburban. I speak as someone who loves living in one of these towns.
The Gardner is one of my favorite museums but it’s not where I’d take a kid exploring Boston. Ditto the MFA, Freedom trail or USS Constitution.
I’ll echo the recommendations for:
Blue Man Group. A total hoot if he hasn’t seen them. Won’t really help him get a sense of Boston but the show is really fun and strange. If you do go look into getting his name on the message board-always a fun surprise.
The North End. The streets are small and good for walking, the pasta fabulous. Might be a good place for lunch.
Newbury St. If he’s not from a big city where designer boutiques are commonly seen it can be kind of fun to check out places like Hermes and Fendi. The people watching is good on Newbury and there are some fun shops, particularly toward the funkier end away from the Public Gardens. Generally better for girls than boys but he might still find it fun.
The Sox if you can get tickets in advance or are willing to wait in line. Kenmore Square, near BU, is an easy walk from Fenway. Perhaps hit the House of Blues for a concert.
http://www.houseofblues.com/boston/#calendarsearch
Harvard Square. Not as funky as it once was but still worth visiting. The Square is literally outside the gates of Harvard, so you can stroll around the Yard then out the gates for lunch at the Border Cafe (unexceptional but decent Mexican in a fun environment a block from Harvard), Fire and Ice, Cafe Algiers (particularly good as a place to rest and have a coffee) or Burdick’s (chocolate, and lots of it) or any of a number of good places to get an easy lunch. If he’s ever listened to Car Talk, the NPR automotive/comedy show you can look for the gilded sign for the law offices of “Dewey Cheatham and Howe.” There are often street musicians on nice summer afternoons and evenings. Lots of fun shops to explore like Newbury Comics. From the Square it’s an easy walk down to the river to sit on the grass and watch the rowers. If he’s a lover of Japanese food you can take the T one stop from Harvard Square to Porter and hit the Porter exchange for one of the sushi or noodle restaurants. Check out the design of the subway station.
Ice Cream. Boston is an ice cream town. JP Lick’s in Harvard Square. Toscanini’s near MIT or my personal favorite, Christina’s, a little north of both.
In another year I might recommend a free outdoor concert or movie at the Hatch Shell (along the Charles but currently closed for renovations).
Parking in Boston can be a pain and lots in some areas are very expensive. Use of the MBTA or a hop-on, hop-off tourist bus would give you some freedom to navigate.
My biggest piece of advice is to post your question on the individual boards for the schools he’s considering. Most of us on the parents forum can’t really tell you where students hang out these days, so our advice is bound to be rather general or outdated.
There have been many great recommendations given! We really enjoy the Harbor area and the North End. Nathaniel Hall/ Quincy Market has a little to much stimulus for me but is fun with all the stores and the street performers.
Boston and Cambridge are really vibrant, great places for anyone to spend time and especially so for a young adult.
I wanted to also concur with the comment about how difficult parking can be. Finding places on the street that are not permit parking only are very hard to come by, and if you do you have to plan accordingly to be back and forth to puts coins in the meter.
The paid lots are typically a $30 to $37 charge after two or three hours. For people like ourselves who live in a rural area, having so much energy being devoted to parking strategies has taken some getting used to.
What’s the purpose of the trip? Is it to show the OP’s son what life would be like if he went to school in Boston or is it more generally a family trip?
I have lived here for most of my adult life (finished grad school here and worked here for most of my career thus far) and one of my two kids goes to school in Boston. I used to be a professor at one of the esteemed schools here and still teach there once or twice a year. If I were showing a kid what school would be like, I’d go to the various school neighborhoods, especially those that are in the cards. Harvard Square, Davis Square, Kendall Square, Commonwealth Ave near BU, the Fenway area (lots of schools here including Emmanuel, Simmons, Mass College of Art, the Pharmacy school (don’t remember the name), a little farther down Wentworth and Northeastern nearby, …, the Longwood Medical area (right next door).
If museums are interesting, throw in a few. MIT’s museums are often very interesting for the non-art folks as is the Peabody Museum at Harvard. (Right now there is an incredibly interesting exhibit at the Fogg with Rothko paintings being restored by light rather than paint, but I’m not sure how long that will be up). If the stadium is interesting, take a tour.
I think Concord and Lexington are quite beautiful and a big part of American history, but I’d pass on that unless the objective is an educational family trip. Probably the same with the Freedom Trail and Boston Common.
I guess you have to be thoughtful about what you show. When ShawSon was a sophomore, I said, “we ought to start thinking about colleges.” We were going to dinner and so I said, “Let’s walk through Harvard.” At the end of the walk, he said, “So is this where you want me to go?”
It would help to know what schools the student is interested in 
@shawbridge Great information. The main purpose is to visit and tour three schools on my son’s list. We have set up information sessions and tours at all three, and at one we were able to also schedule a full engineering information session and tour of labs. I had to laugh at your walk through Harvard scenario. It’s not on my son’s list but we’ll do a walk through and visit the museum. It’ll be interesting to see if his mind changes.
The information all of you have provided above on both college specific neighborhoods to visit as well as historical and touristy spots is very helpful. We plan to do a little of both since the last time my son was in Boston he was only 2. And yes after some research we decided not to rent a car. We’ll either cab it, take the T or walk. I enjoy walking and I rack up a lot of miles on my fitbit during college visits.
CC is by far the most useful site for college information. Thanks to all for taking the time to post.
I agree. We looked at Wellesley, Tufts and Brandeis. (D wound up at Wellesley.) Sure, we did the requisite tour of Boston and had a great time - but she spent most of her time in the town of Wellesley and frankly we should have concentrated more on what that offered to a college student (which isn’t all that much - it’s an upscale suburb geared towards affluent stay-at-home mothers, not 18 - 22 yos). There’s not much to dislike about Boston, but how much time are they really going to spend there if the school isn’t right there?
Sorry - above response was to an earlier post. What I’m agreeing to is the concept that it’s most important to spend time / evaluate the neighborhood where the school is – not downtown Boston as a whole (unless of course the school is in downtown Boston!). There’s no reason that can’t be combined with a “let’s explore Boston as a family” but keep in mind that that is something entirely different.
And can I ask? Why does everyone ooh and aah over Cambridge? What’s so impressive about it? It leaves me “eh.”
I think it’s enjoyable to visit some fun areas as well as college areas when you are in a new town. My mother and I always visit a site or two when we go on college visits. It would be pretty boring to fly to various new towns and only see the college. Sure the OP may not be going to downtown Boston every weekend but may be visiting on occasion. Especially when out of town visitors come in. It would be strange, in my opinion, to go all the way to Boston and not experience some of the things that make Boston unique. I also have to add that I would not go to a concert with my mother as some poster suggested above. Nor would I take the time to see Blue Man Group which can be seen in any town.
You probably don’t have time to visit many places. Each place takes at least 3-4 hours.
For meseums, I vote for Boston Museum of Fine Arts, Boston Museum of Science, Harvard Museum of Science, MIT Museum, Boston Aquarium.
For leisure walking: Boston Commons, Harvard Bridge, Memorial Drive along Charles River, Harvard Square.
I agree it’s enjoyable to visit some fun areas - we “did” Boston and Wash DC as tourists when taking our kids there for college visits.
But I too would not bother to do Blue Man Group which can be seen in tons of places, and isn’t anything unique or special to Boston.
Totally agree. Best ice cream in the Boston area!! If you’re at Toscanini’s, stop at Mary Chung and get DunDun noodles if you like spicy Chinese food. Both are near MIT.
I’d concur with what others have said above–you should have your son spend time in the area around the colleges/universities that interest him. My H’s office is on Concord and while it’s a great suburb full of interesting history, it’s highly unlikely that a college student going to school in Boston would ever spend time in Concord. My T went to Tufts–we live in the town right near Concord. She brought roommates and friends home for dinner when she was a freshman, but that was it. There’s not much in Lexington or Concord for young people. When my D was at Tufts she spent most of her time in Somerville/Davis Square.
I agree with your decision not to rent a car. Driving in the Boston area is difficult (although the advent of Google Maps and Waze make it better). Cabs are so so. The T is good for certain trips like those on the Red Line but can be slow for trips on the Green Line. Uber and Lyft work well in the Boston area. With my encouragement, my D uses Uber a lot (and Lyft when surge pricing is on Uber), particularly at night when she is coming home from a late night of studying or working a shift at a hospital, clinic, school etc. or wherever she is working. If you don’t already have them, you can set the apps on your phone and set up your account.
What’s so special about Cambridge, @Pizzagirl? For a college kid? It’s relatively small (population 100K) with lots of restaurants, ice cream stores, a few breweries, and other things to do given the size. Plus, lots of college kids. So, options catering to students (unlike Wellesley) as well as others, things to do, etc. It’s not NY, but things are available and relatively easy to get to, and I didn’t need or want as many distractions as NY can provide when I was in school. Harvard Square has gotten a bit homogenized over the years, but Central Square is pretty vibrant and Davis Square has become so.
For an adult, it all depends upon your definition of what’s interesting, but for me, Cambridge and the Boston area generally has the highest proportion of interesting people per capita. Because of Harvard, MIT, Tufts, and the other schools, the biotech firms that largely spun out of MIT/Harvard, the consulting firms, the finance firms, lots of folks doing interesting public oriented things, software firms, etc., the people I meet regularly are doing things that are interesting. We’ll run into people working on a cure to malaria, trying to chart out the way universities have to change, mediating in garden hotspots like the Ukraine, designing algorithms for sophisticated bond arbitrage, setting up entities to coach entrepreneurs in disadvantage areas of Massachusetts in one case or create economic growth in cities around the world. I would not say the same about Boston if I were a visual artist (-- or that, it would be better to be in NY, Berlin, LA. I travel all over the world perhaps too much (this month, I’ve been in Basel, The Hague, London, Princeton, and Frankfurt – hopefully nowhere else) and no place else seems close – San Francisco/Silicon Valley is similar but in a more limited domain.
One other thing: we found hanginig around campus to be more useful than touring cities, or even more useful than formal tours and info sessions. Cafeteria, college green, bookstore were our choices. Then most every college has a neighborhood, or a street, where students shop or get coffee. I would target these as well.
Much as I love the MFA and swan boats, they won’t tell your son much about the college experience.
I agree with @compmom. We had very informative conversations at one school when we took the tour guide out to lunch after the tour and in the campus bike shop at another school.
It would help if we knew the schools. BU and Northeastern are fairly close to each other. I’m another one who has never been as enamored of Harvard Square, though we’ve been spending more time there lately. IF you’re there around lunch time, I highly recommend Crema Cafe. It’s a coffee shop/sandwich shop - interesting, good food. And my Northeastern daughter’s favorite restaurant in Harvard Square. A great place to eat in Davis Square (if you’re looking at Tufts) is Amsterdam Falafal - if you like falafal. All they have is falafals and salads. Small place with some tables. And JP Licks, one of our great ice cream places, is across the street.
I would go to the waterfront - Quincy market, the north end, get canoli at Mike’s. Another area frequented by college students. Anthem is a good sit-down restaurant if you decide to eat in Quincy market but don’t want the (huge) food court). Or the north end.
I also agree with skipping Lexington and Concord. THe history is ok but there’s more in the city.
Have fun. Boston is a great city for students and parents alike.
@compmom Agree about hanging out on campus after the formal tours. We have learned so much on our college visits by having a drink or snack in the cafeteria or if a nice day enjoying a cup of coffee in the quad. You can get a real feel for the campus vibe this way.
@shawbridge Thanks for the suggestions for Uber and Lyft. I had not heard of Lyft but I will download both apps to my phone.
When I was a student at Harvard, lots of students never stepped foot in Boston. I took some architecture classes that got me out, I went to hear music a handful of times, got to the various art museums (Gardener Museum - lovely and not overwhelmingly large as it was a house originally), Museum of Fine Arts, the modern art museum as a spectacular view of the harbor. My kid’s favorite museum in Boston is the Science Museum (more accurately the only one they are ever willing to step foot in!). If you read Make Way for Ducklings you need to go to the Public Garden! The newly renovated Fogg Museum at Harvard is almost certainly worth a visit. All that presuming your kid likes art at all - if he’s looking at engineering schools maybe not!
We really like eating the Ethopian food at Asmara near Central Square in Cambridge. It’s sort of a sourdough pancake/bread topped with various spicy - curry-like toppings. Eat with your fingers.
For good lobster rolls try: James Hook and company in downtown Boston.