“and about a zillion others” YES!
Too many variables that you need to consider. Cities come in many sizes and the school may dominate the city life. Madison is an excellent city home to an excellent university (it also is a state capitol). Now let others champion their favorites as well.
“Urban” Hmmm. Many ways to be that as well- doesn’t need to be a concrete jungle. Nor does it need to be a rigid grid within a rectangular border. A squiggly border but with contiguous buildings can be great.
Barnard, Fordham
University of Washington
Vanderbilt
U of Minnesota
Reed is beautiful (its own canyon with lake) but it’s out in the suburbs.
To my mind, MIT’s campus is pretty well defined.
Harvard sprawl’s all over Cambridge and Allston (and beyond) so I would definitely not consider it well-defined overall, but within that sprawl there are several well-defined “sub campuses,” Harvard Yard perhaps being the most notable oasis.
University of British Columbia (Vancouver).
Rhodes College in Memphis
NC State, U of South Carolina (Columbia), Emory
Fordham Rose Hill has a beautiful, traditional, enclosed campus in urban area (Bronx). Public transportation to Manhattan easily accessible.
Tulane has a beautiful, traditional campus within a city, not near downtown, but in a very nice part (the best neighborhood IMO) of the city and across the street from a really nice park. It is on the streetcar line with easy access to downtown.
Johns Hopkins has a very pretty, well defined campus in an urban area.
Virginia Commonwealth University in Richmond, VA.
Drexel U and Temple U in Philadelphia.
George Mason U, in suburban Fairfax, VA, close to DC.
Providence College in Providence, RI.
Franklin and Marshall College in Lancaster, PA.
Notice how many diverse choices there are? You need to focus on other criteria first to limit your choices to a manageable number. Figure out a region based on many factors. Those will include costs, distances from home, climate, regional flavor and so many more. Then look at cities within that region. Figure out the size of the city that appeals to you. btw- a great campus does not need a great city surrounding it as you find plenty to do on campus. Remember that most of your time will be spent being a student, not enjoying city amenities. There is a reason top schools do not need a great city.
Some of these campuses are a lot more defined than others. I am very familiar with the Drexel and Temple campuses, and I would not call them “defined,” unless the only standard of comparison was NYU. Penn, which is adjacent to Drexel, has a sizable core that feels separate from the surrounding traffic grid, and has a lot of distinctive academic architecture and green open space. That just isn’t true with Drexel . . . although with Penn so close, and three major academic hospitals, a science business incubator, and another smaller university tucked away in there, it’s certainly part of a vast area where academic institutions predominate.
Also, some of these campuses are a lot more urban than others. George Mason is a meaningful shuttle ride from the very end of a Metro line. That makes it a lot more urban than, say, Williams, but not anything like “urban.”
A former poster to whom this mattered said she wanted a central quad where she could stand in the middle and only see college buildings. It was okay if the campus bled into the neighborhoods on the edges.
Certainly, when I was in college both when I lived at Radcliffe and when I lived in one of the River Houses I was going through parts of Cambridge that were not actually owned by Harvard. I thought that was a plus. I crossed a few city streets to get to classes, but I think all my classes were still adjacent to other Harvard owned buildings. There’s definitely a central core - and a freshman could probably survive without stepping foot onto a real street.
Brown
@mathmom
“when I lived at Radcliffe and when I lived in one of the River Houses I was going through parts of Cambridge that were not actually owned by Harvard.”
You mean there is such a thing? Places in Cambridge NOT owned by Harvard? 
Well, they might have been owned by Harvard, but they didn’t house Harvard functions. 
Personally I feel GW is very well “defined.” They have banners, signs, statues, etc all over the campus. While it is a very urban feeling campus almost 100% of the buildings in their area have been purchased by GW. When I went there I actually felt like I was in a campus (and we do have a small quad).
That said, it is not at all separated from the city. It is part and parcel of the larger community that walks/drives through the university every day.
I think MIT is the biggest property owner in Cambridge. They pay about 5x the taxes that Harvard does.