On a plan of the town from about 1531, a chancel appears, and seals affixed to the city and college charters bear representations of other buildings attached.
The cathedral was finally completed in 1318 and featured a central tower and six turrets; of these remain two at the east and one of the two at the western extremity, rising to a height of 30 metres (100 feet).
In June 1559 during the Reformation, a Protestant mob incited by the preaching of John Knox ransacked the cathedral; the interior of the building was destroyed.
St Rule's tower is located in the cathedral grounds but antedates it, having served as the church of the priory up to the early 12th century.
Originally, the tower and adjoining choir were part of the church built in the 11th century to house the relics of St Andrew.
Built in grey sandstone ashlar, and (for its date) immensely tall (33 m), it is a land- and sea-mark seen from many miles away, its prominence doubtless meant to guide pilgrims to the place of the Apostle's relics.
The tower was originally ascended using ladders between wooden floors, but a stone spiral staircase was inserted in the 18th century.