The Church of St Regulus (or St Rule) was a much smaller building than the Cathedral whose ruins are pictured above. Until modern times the Cathedral was the largest edifice ever built in Scotland and probably contained the largest collection of medieval art ever gathered together in Scotland. Building started in about 1160 and it began to be used as a Cathedral and priory some 70 years later. After 110 years, it was nearly complete but the West gable was blown down in a storm. The Cathedral was not finally consecrated until 1318, in the presence of Robert the Bruce.
The great Cathedral was a centre of pilgrimage in Scotland during the High Middle Ages, principally because of the presence of the relics of St Andrew.