[1] Documentary confirmation of the Episcopal church Ecclesia sanctae Mariae urbis Constantiae is dated to the mid 8th century.
There is clear evidence indicating that it was located on the Cathedral Hill, where a late Romanesque fortification with an adjoining civilian settlement had been established.
Its reconstruction took place under Bishop Rumold von Konstanz [de] (1051 - 1069), with the eastern transept and three naves separated by 16 monoliths.
The radical iconoclasm instigated by the reformer Huldrych Zwingli in nearby Zurich, caused the destruction of artwork in the Cathedral.
The subsequent centuries saw the addition of more paintings, wrought iron gates and sculptures, as well as the replacement and repair of destroyed items.