The more recent church, which currently is united to the other and gives the appearance of a single edifice, was constructed along the naviglio (navigational canal) bank in the 15th century, and then called Ducal Chapel.

It was commissioned by Duke Gian Galeazzo Visconti in order to provide a holy edifice and dedicated to St Christopher, the protector of ill people.

The façade sports the Visconti coat of arms, while the older church has the heraldic symbols of Cardinal Pietro Filargo, then bishop of Milan and later pope as Alexander V. In 1405 the counterfaçade of the Ducal Chapel was decorated with a Madonna Enthroned and Saints and a Crucifixion inspired by that in San Marco of Milan.

The façade of the Ducal Chapel has a simple portal flanked by Gothic mullioned windows, according to a model established by Guiniforte Solari, and traces of frescoes of Saints from the 15th century.

The apse houses frescoes of Bernardino Luini's school, portraying the Father with Angels and the symbols of the Evangelists, and Saints.