^ It is cool. But not unique in any sense. I started taking grad classes as a first quarter freshman at Stanford 35 years ago. I was officially a graduate student by the end of my sophomore year due to submatriculation and credits accumulated.
^ renaissancedad, as an undergrad at Stanford, could you have taken classes at Stanford’s law school without special dispensation? At Stanford’s graduate business school? Or at any of Stanford’s graduate and professional schools other than in the field in which you submatriculated, such as schools comparable to Penn’s Graduate School of Design, School of Public Policy and Practice, or Graduate School of Education for example? I think what others are saying here is that although other top schools do provide interdisciplinary opportunities for the average undergrad enrolled there, NONE does it to the extent, and with the breadth and depth, that Penn does. Any Penn undergraduate, in ANY of Penn’s four undergraduate schools, can easily take courses in any of the other 3 undergrad schools (College of Arts and Sciences, School of Engineering and Applied Science, Wharton, and Nursing), and in most of the graduate and professional schools including the Law School, School of Design, School of Public Policy and Practice, and Graduate School of Education. And all they have to do is register for the class. No other requirements in terms of credits accumulated, submatriculation, or special permission. AND, as PennCAS2014 has pointed out, Penn started the Penn Integrates Knowledge (PIK) professorship program under current president Amy Gutmann less than 10 years ago, and already Penn has brought in 16 world-renowned scholars to fill these specially endowed professorships that each hold interdisciplinary appointments in at least two of Penn’s schools:
https://pikprofessors.upenn.edu/meet-the-professors
And there are more to come. Not to mention that this is just the latest program to build on Penn’s preeminent position as a pioneer in interdisciplinary education and research that transcends the traditional boundaries of the time, a tradition that goes back literally to its founding by Benjamin Franklin and his extraordinary “Proposals Relating to the Education of Youth in Pensilvania” published in 1749. That document essentially became the blueprint for the founding of what would eventually become Penn, as well as the modern conception of higher education:
http://www.archives.upenn.edu/primdocs/1749proposals.html
What have followed since have been many examples of Penn forging new interdisciplinary connections and breaking what were then traditional boundaries in higher education, including the first medical school in North America in 1765, the first law lectures at an American college in 1790, the first collegiate school of business in the world (Wharton) in 1881, not to mention the first teaching hospital in the country, the first psychology department in the country, the first collegiate journalism course in the country, etc. Unlike any other university in the world, interdisciplinary study has defined Penn’s ethos since its founding by one of this country’s first and most famous polymaths and Renaissance men (as opposed to a renaissance dad 
).
Again, many other schools offer interdisciplinary opportunities to undergrads, but none of them DEFINE themselves by, have as rich a history in pioneering, or have institutionalized and incorporated interdisciplinary education into their undergraduate programs to the extent that Penn has and does.
^ Boy the Koolaid on this thread is thick! Obviously Penn is without doubt without peer as a university, and none other in the land comes close!
Penn is a wonderful, wonderful institution. No doubt. I’m a huge fan. And it’s a great place for interdisciplinary studies. But all this “none of them DEFINE themselves by” stuff is silly. When I applied to colleges Penn wasn’t particularly known for interdisciplinary studies. It certainly wasn’t “defined” that way. It was pretty much regarded as a “lesser Ivy” + Wharton, and not much else. [And Duke was basically just a prominent southern school at the time.] There was absolutely no hype about interdisciplinary studies and their importance when I applied to Penn. None of this “one university” rhetoric. I turned Penn (among others) down for Stanford because I found Stanford considerably more flexible and open, and more interdisciplinary in its approach at the time. There were no separate undergraduate schools at all, and there was considerable freedom. And certainly, I took courses at the medical school without having to request permission, and without being submatriculated there. I never encountered a single restriction at Stanford for students who were capable of doing the work.
Many of Penn’s interdisciplinary endeavors are more recent than when I applied. Huntsman, Vagelos and Jerome Fisher didn’t exist 25 years ago, and much of the rhetoric of Penn being such a unique interdisciplinary place didn’t become commonplace until Amy Gutmann took over as president. My wife is a Penn grad and I had 2 cousins go there, and none made any mention of Penn being particularly interdisciplinary, or recall it that way. But all 3 loved it.
Penn deserves tremendous credit for re-defining itself in a way that plays to its strength and differentiates it from most of the other Ivies. I give it full credit for that, and it’s truly an outstanding place for anyone interested in interdisciplinary studies. But I don’t believe that not always been “defined” the way you say. I consider that to be to its credit - if I were applying now, I’d be giving Penn much more serious consideration than I did 35 years ago. And as much as I loved my experience at Stanford, I worry that it’s success in engineering and CS has threatened to overpower the balance of the school.
At any rate, I’ll bow out of this discussion, and leave the zealous to believe that theirs is the only true religion. From my perspective, Penn is a great place for interdisciplinary studies, and should be high on the list of anyone with those kind of interests. But it’s not the only place, and not inherently “better” or “more interdisciplinary” or “more defined by interdisciplinary” than some other great places. That’s all.
Kool-Aid tastes good
^ renaissancedad, your knowledge of and experience with Penn in the 1970s was significantly different than mine. I started at Penn in 1974, and the “One University” concept was very much trumpeted by Penn even then. In fact, here’s a report from January 1973 about the “One University” concept and policy:
http://www.archives.upenn.edu/primdocs/uplan/paoneuniv1972.pdf
It started LONG before the presidency of Amy Gutmann, and was very much championed by her predecessors Martin Meyerson, Sheldon Hackney, and Judith Rodin. And, as I said previously, it really built upon Penn’s longstanding history and tradition of interdisciplinary education and research–and combining theoretical, academic, and practical education–stretching back to its founding. In fact, Penn had undergraduate programs in business, nursing, and allied medical professions (which ended in the late 1970s) when such programs would have been unheard of–and in many ways still are–at any of its peers. In fact, when I started at Penn, its social science departments were actually housed in the Wharton School, believe it or not, and Penn had already pioneered interdisciplinary academic departments in Regional Science, Peace Science (it’s true!), American Studies, and the History and Sociology of Science, among others. Penn’s Biological Basis of Behavior program was “created in 1978 as one of the first neuroscience undergraduate programs in the country, [and] allows students to explore a broad range of topics in the neural sciences through courses taught by faculty and staff in several departments in the School of Arts and Sciences and the Schools of Medicine and Veterinary Medicine.” http://www.sas.upenn.edu/bbb/ And again, very few, if any, of its peers had such programs at that time.
So you may have been unaware of it when applying to college in the 1970s, but Penn was already one of the leaders, and perhaps was THE leader, in formalizing and institutionalizing interdisciplinary education and research by the 1970s. Not Kool-Aid–just well documented history and facts. 
One minor correction: Management and Technology (commonly called M&T) has been around for almost 35 years. Looking at Dr. Hamilton’s CV, it looks like it started in 1978. I don’t know when they added the Jerome Fisher appellation though.
For what it is worth I graduated in 1957. Although I was in CW (College for Women - merged in the 70s I think with the College - now CAS). I took almost as many courses In Wharton than I did in CW. Wharton and SEAS (the Moore School of Engineering) started admitting females in I think my jr. year.
So the tradition of taking courses in all the colleges is not recent.
The Ivy League was relatively new and Penn was equal to Columbia and Brown then. It Was Harvard, Yale, Princeton, then Penn Columbia and Brown, then Dartmouth and Cornell.
@amanivy i don’t think much has changed since then apart from the fact that brown is considered along with dartmouth and cornell at the bottom tier. penn and columbia are still in the middle and HYP on top.