The dome stands on the top of the 40-metre high basilica and is entirely constructed of prebuilt panels decorated with a continuous series of zigzags that can also be interpreted as endless repetitions of the letter "M" for Mary. The arrangement of the panels in rays imitates the petals of a lily.
The light floods from the central opening of the roof lantern and illuminates the whole dome. Sixteen triangular windows form an intensely bright circle that makes the dome ethereal.
The exterior is covered in stone up to the level of the loggia with arched openings. The loggia and the roof lantern are also made of stone while the perimeter is covered in copper.
The windows of the dome are made of concrete and coloured glass by the Swiss painter Yoki Aebischer and represent: the Apostles, the Saints Joachim and Anna, Saint Ephrem the Syrian, Saint Bernard of Clairvaux.