"The greater Philadelphia region is the second-largest medical research and education centre in the U.S. More than one third of the conventions and meetings held in the region are life sciences-related. One out of every six doctors in the country was trained in Philadelphia, and 80 percent of Americas pharmaceutical firms, as well as 80 percent of the worlds major biotech companies are located within a two-hour drive of the city. Philadelphia faculty and graduates pioneered the use of X-ray, helped identify the first colon cancer gene, invented ultrasound gels, discovered the existence of chromosomes and endorphins, founded six of the top 10 pharmaceutical companies, and continue to run the countrys number one childrens hospital."
http://www.philadelphiausa.travel/LQxFeJ
"More than 150,000 students attend college in Philadelphia, while one out of every six U.S. doctors is trained in the city. "
http://www.cvent.com/destination-guide/philadelphia/
"The region ranks third in the nation for the number of health professions and related degrees conferred. One out of every six doctors in the country was trained in Philadelphia."
http://www.onebigcampus.com/pdf/fsb_ls.pdf
Also, the American College of Physicians (ACP) is located in philly. The ECFMG is located in Philly, and Philly was the site of the original Step 2 CS site. American Board of Internal Medicine is in Philly. American Board of Surgery is in Philly. American Board of Allergy and Immunology, American Board of Plastic Surgery, and American Board of Ophthalmology are located in Philly (well, technically Ophthalmology is in Bala Cynwyd, a neighboring suburb ... if you cross the street from PCOM, you're in Bala Cynwyd)