Boleslav II, Prince of Bohemia, shared a dream with Bishop Adalbert, leading them to a divine source. They would meet in front of a log that they would move and from which water would spurt. The legend is based on fact: upon his return from Italy in 993, Adalbert founded a convent here for the Bishop's martyr, it became a centre of pilgrimage and a Romanesque basilica was built, which was transformed into a Gothic church and refashioned in the Baroque style in the 18C.