The Texas Medical Center is the largest medical center in the world with one of the highest densities of clinical facilities for patient care, basic science, and translational research. Located in Greater Houston, the center contains 54 medicine-related institutions, including 21 hospitals and eight specialty institutions, eight academic and research institutions, four medical schools, six nursing schools, and schools of dentistry, public health, pharmacy, and other health-related practices. All 54 institutions are not-for-profit. Among the affiliated medical schools are the University of Texas Health Science Center at Houston, Baylor College of Medicine, Texas A&M College of Medicine, and University of Texas Medical Branch in Galveston. The center exceeds one thousand acres (or 1.562 square mile) in size. Some member institutions are located outside of the city of Houston. The Center is where one of the first and largest air ambulance services was created and where one of the first successful inter-institutional transplant programs was developed.