The Glasgow Cathedral is one of the few medieval Scottish churches to survive the Reformation. It dates back to about 590 AD, when Saint Kentigern (also called "Saint Mungo") arrived in the area to become the bishop of Strathclyde. He founded a small church on this site, which is now the location of the "lower church". His congregation (known as "Clasgu" or "dear family") grew into what eventually became the town, and then city, of Glasgow. This spot can be seen by descending a staircase in the Cathedral. The date of St. Mungo's death is given as January 13, 603. The original church was built of wood but was changed and enlarged over the next 500 years before any stonework was added. The first stone of the church was consecrated in the presence of King David I in 1136. Over the next 800 years, parts were destroyed by fire, several choirs were added, towers were built and dismantled, and stained glass windows were added. Pieces are still occasionally added to the Cathedral to this day. During the Reformation period of 1560, when many churches were looted, vandalized, and destroyed by mobs, this particular cathedral was so close to the hearts of the ordinary people of Glasgow; they took up arms to defend it themselves.