At the bottom of Gellert Hill is the "Cave Church". They have a self-guided tour you can take. It's amazing how well it's been preserved after so many years. The Pauline Monks worshiped there for many years but in 1951 the entire Pauline order of Monks was arrested by the communist government. The head monk was executed, the rest were put into labor camps and the church was sealed behind an eight-foot wall of concrete. In 1989, after the fall of communism in Hungary, the wall was broken down and the cave reopened.