St Andrews Cathedral is a historic church located in St Andrews, Scotland. Built in the 12th century, it was once the largest cathedral in Scotland and served as the center of the medieval church in the country. The cathedral is known for its impressive ruins, which include the remains of the nave and the iconic St Rule's Tower. The cathedral was dedicated to Saint Andrew, the patron saint of Scotland. It played a significant role in the development of Christianity in the region until the Protestant Reformation in the 16th century, which led to its decline. Today, it is a popular tourist attraction and a symbol of Scotland's rich religious heritage.