Yes, Glasgow historically had a major fortification known as the Bishop's Castle (or Glasgow Castle), located in the Townhead district directly to the west of Glasgow Cathedral. Originally built in the 12th century, it served as the high-value residence for the Archbishops of Glasgow for centuries. The castle was a site of high-intensity conflict, changing hands multiple times during the Wars of Scottish Independence and even being captured by William Wallace in 1296. It fell into disrepair after the Reformation and was eventually demolished in 1789 to make way for the Glasgow Royal Infirmary. Today, a stone from the original keep and a commemorative plaque in Cathedral Square mark its former location. Another survivor is Crookston Castle in the south of the city, which is the only remaining medieval castle ruin in the City of Glasgow, offering travelers a high-value "hidden" look at the city's ancient defensive history and stunning views from its hilltop position.