The cathedral was almost not sited in Glasgow at all. The obvious first choice was Govan, which in the 11th Century had a pre-eminent religious status within the area.
But when David I became king, he rejected Govan because it was associated with the previous royal dynasty. David needed his own power-base so, sometime between 1113 and 1124, he created the position of Bishop of Glasgow, and began building a cathedral as the centre of the diocese. Govan declined.
Glasgow's elevation to the bishopric – thus becoming the principal church in the west of Scotland – marks the moment the town started to be a force in the land.
In 1175, it was made a Burgh of Barony, meaning that it could control its own trade and politics.
The older Royal Burghs of Dumbarton and Rutherglen had their noses put out of joint – but Glasgow had arrived.
The diocese of the Bishop of Glasgow stretched to the border with England, incorporating 200 parishes and generating huge sums in rents and other income.
In Glasgow itself, the bishops had all the power.
Serious fires and the scale of the project meant the cathedral was a constr-uction site for centuries.
The first cathedral was dedicated in the presence of King David I in 1136. What we see today is largely the third building, mostly built in the 13th century, although major alterations continued for another 100 years.
The cathedral's website, www.glasgowcathedral.org.uk, says: "The present building was consecrated in 1197. Since that same period the cathedral has never been unroofed, and the worship of God has been carried out within its walls for more than 800 years."
Next week – facts about the cathedral.