In 1344, he was summoned to Prague from the papal court of Avignon by Charles IV to lead works on the newly founded Saint Vitus Cathedral.

The role of its master mason and Charles' head architect fell to then twenty-three years old Peter Parler.

On 21 November 1344, John of Luxembourg laid the foundation stone of St. Vitus Cathedral in connection with the elevation of the Prague bishopric to an archbishopric.

Two of the king's sons, Charles IV and John Henry, were present, as was the Archbishop of Prague, Arnost of Pardubice.

In the south, he began the construction of the Chapel of the Holy Cross, which was initially located separately outside the part of the cathedral being built.

The young Peter Parléř, only twenty-three years old, was born in Swabian Gmünd and came from a distinguished family of builders.