This humble beginning evolved into a significant pilgrimage destination during the Middle Ages. In the 12th century, construction began on the grand cathedral atop St. Mungo's burial site. Although consecrated in 1136, it had to be rebuilt and consecrated once more in 1197 after a devastating fire.
Over the centuries, Glasgow Cathedral expanded under the guidance of various bishops, who oversaw necessary restorations. William Turnbull, among them, founded Glasgow University in 1451, with its inaugural lectures held in the cathedral's chapter house.
During the Protestant Reformation in the 16th century, the cathedral underwent significant changes, losing its Catholic adornments and buildings. However, it continued to serve the new faith, remaining operational and protected by Protestant ministers against vandalism and decay. This care ensured the cathedral's remarkable preservation to the present day.