Oslo Cathedral School (Norwegian: Oslo Katedralskole, commonly called 'Katta') is one of Norway's oldest and most prestigious upper secondary schools, founded in 1174 by Nicholas Breakspear (later Pope Adrian IV). Originally a medieval cathedral school attached to Oslo Cathedral providing Latin and theological education for ecclesiastical roles, it has evolved into a modern, highly selective public gymnasium emphasizing rigorous academic programs in humanities, sciences, languages, and international baccalaureate options. Located in Oslo's historic district near the ruins of the old cathedral, the school admits students based on academic merit and is renowned for fostering intellectual excellence, critical thinking, and leadership. Its notable alumni include Norwegian kings (e.g., Harald V), prime ministers (e.g., Jens Stoltenberg), Nobel laureates, and prominent figures in arts, sciences, and society, underscoring its role in shaping Norway's elite. As a state-funded institution operating under the Norwegian Directorate for Education and Training, it balances deep historical ties to Norwegian cultural heritage with contemporary pedagogical standards, though its selective nature occasionally draws criticism in Norway's egalitarian education system.