It is one of the largest urban universities in the country, and consists of 11 senior colleges, 6 community colleges, and one each of: graduate school, law school, and medical school.
There are about 200,000 students working for degree credit, and another 200,000 or so doing adult or continuing education courses.
CUNY has campuses in every one of the five boroughs of New York City.
Colleges that are part of CUNY include (with location in parentheses):
More detailed info on each of the colleges, as well as links to the specific websites, and the addresses of the colleges, can be found at the CUNY website (http://www.cuny.edu)
A good bunch of those are community colleges, but a few are actually pretty respectable colleges (nothing against anyone who goes to a community college-- just there is a difference between that and, say, a state college). Those include Hunter College, Baruch College (Which is a pretty cool business school-- they just got a new building across the street from the 69th Regiment Armory, and since I go to the latter pretty often, I had the pleasure of seeing the new building complete.), John Jay College of Criminal Justice (A good half or more of the students are cops, firefighters, or law enforcement officials-- which makes it a pretty interesting college experience.), and Brooklyn College (They have a nice law program, and their student government is pretty prominent.)
There may be a few others to add to that short list. If you think so, /msg me and we'll talk.
If anyone tells you that CUNY stinks, they are pretty much dead wrong. The faculty and students of CUNY have earned a whole mess of awards, including Pulitzer Prizes, Nobel Prizes, and Guggenheim Fellowships, just to name a few. More details on this are on the website. To cut the crap, as it were, it can be a great place to be if you want it to, especially if you're in one of the colleges I listed in the latter listing.
CUNY was founded in 1847.
Sources: CUNY Reference Booklet
Friends in CUNY (Both Brooklyn College and John Jay)
http://www.cuny.edu (NOTE: I did not copy and paste anything. For the list of colleges, I actually typed it out just out of the extra bit of effort. Also, I did not include some of the more detailed info, like addresses, because statistics are bound to change, and I don't think addresses would be appropriate to node here.)