The Citadel, also known as the Hightower, is both the headquarters of the Order of Maesters - scholars who advise lords of the Seven Kingdoms on matters scientific, medical, and historical - and the seat of House Hightower, vassals of House Tyrell and rulers of the city of Oldtown. The Citadel was founded many centuries ago to promote and increase learning and knowledge in Westeros. It is administered by the Conclave, the ruling council of archmaesters. The Citadel is also where young men from the entire continent are trained to become Maesters.