The University of Oxford is a collegiate public research university in Oxford, United Kingdom. Established in the 12th century, it is the oldest university in the English-speaking world. Oxford developed from a group of scholars who congregated in the city of Oxford, and it has a long-standing historic rivalry with the University of Cambridge. Together, these two institutions are commonly referred to as "Oxbridge". Oxford is made up of a federation of 39 semi-autonomous constituent Colleges and over 100 academic departments organized into four divisions. The university is consistently ranked among the top universities in the world and is a member of numerous academic and research associations. Oxford forms part of the “golden triangle” of leading UK universities, alongside Cambridge and Imperial College London. The university has educated a remarkable number of notable alumni, including world-renowned scientists, writers, politicians, philosophers, and heads of state. As of recent counts, Oxford alumni and faculty include more than 70 Nobel Laureates, 3 Fields Medalists, and multiple British Prime Ministers. Oxford graduates have also achieved significant accomplishments in sports, arts, and global leadership.