Glasgow Cathedral. Glasgow Cathedral is one of the city's most important buildings as it marks the site where Glaschu was apparently founded by St Mungo in the 7th century. The story goes that Kentigern (St Mungo) was the first bishop of this area. The cathedral was consecrated in 1136. It was mostly built during the 13th century and took decades to build. There was once another tower and spire near the front, and in the 17th and 18th centuries it was surrounded by many houses and the Bishop's Castle. The whole area was gradually cleared and re-built with new buildings like the Royal Infirmary. Now that the precinct has been modernised, the Cathedral looks more settled again. It is just as splendid on the inside, where you can see fine examples of stained glass and carved stone.