To put it simply, Columbia is in Harlem. For what it's worth it's in a fairly nice part of Harlem, and all of Harlem is already no longer the crazy deserted crime infested Harlem of the 80's. But, it's still obviously not going to be the best part of town.
I'm not sure where Cirrus is getting his information, but I'm a P&S student, and neither the medical center campus or the undergrad campus are in Harlem.
The medical center campus (i.e. P&S campus) is in Washington Heights, which is north of Harlem, in the little tail that makes up the north end of Manhattan. North of Washington Heights is Inwood, south is Harlem. Inwood is a quiet, nice residential area. Harlem is... well, Harlem. South Harlem (110th -125th St) on the west side has experienced significant gentrification. Bill Clinton's office, for example, is somewhere around there. Fancy restaurants and organic grocery stores have moved in. Real estate agents are now calling it SoHa. East Harlem is still a fairly dangerous place, as Manhattan goes. Harlem north of 125th is also a little sketchy.
15-25 years ago, Washington Heights was very dangerous, with a lot of drug related violence. Now people only consider it to be 'a rough part of town' because everyone speaks spanish and there are domino games out on the street.
Most first year students live in Bard Hall, a dorm shared by medical, nursing, public health, and other health sceince students. Second year, you move to university owned apartments on the medial center campus or find an apartment in manhattan. University housing (dorms included) ranges from six to eight hundred a month. The dorm is ugly, old, and painful. The apartments, however, are sick. They're spacious, well kept, relatively new, and have gorgeous views.
Students that move off campus can be found in many different places. Some find apartments in the immediate area. This is a safe option, and I believe prices are comparable to what the university charges. Some choose to move south of the medical center, which is probably cheaper but requires more vigilance walking home at night. A dental student living around 150th was robbed some time this school year when two men followed him from the subway. A fair number of students live in Morningside Heights, where the undergrad campus is. Morningside is bordered on the east by Morningside park, which separates it from south harlem (SoHa
). South is the upper west side. Morningside is very safe and has the feel of a college town. There was a pretty disturbing incident recently that involved a columbia student, but she lived in hamilton heights, an area of north harlem.
Commuting to the medical center campus from other areas of western manhattan is fairly easy because it's on both the red and blue lines. The A train runs express from 59th to 125th, and is a quick way to the medical center if you live south of the park.
I could go on and talk about affiliate hospitals, but let me just mention one thing. Most of the hospitals are in safe areas. We do, however, rotate through Harlem Hosptial, which is on 135th St between Malcom X and 5th Ave. I understand it's a pretty rough area, but I haven't been there yet. I know the administration pays more attention to call schedules etc. there (to ensure there is a safe transportation when students are heading home).
If I had to rank the safety of the areas surrounding NYC schools, I would say Downstate is going to be the least safe. I'd put Einstein next, though I have no personal experience there. Columbia and Sinai are tied, followed by Cornell and NYU (also tied). I don't know a damn thing about any schools in the surrounding area. You also have to remember, NYC is now one of the safest major cities in the country, so this is all relative.