 Charles was originally buried in the chapel of the Monastery of Yuste, but he left a codicil in his last will and testament asking for the establishment of a new religious foundation in which he would be reburied with Isabella.Following his return to Spain in 1559, their son Philip undertook the task of fulfilling his father's wish when he founded the Monastery of San Lorenzo de El Escorial.After the Monastery's Royal Crypt was completed in 1574, the bodies of Charles and Isabella were relocated and re-interred into a small vault in directly underneath the altar of the Royal Chapel, in accordance with Charles's wishes to be buried "half-body under the altar and half-body under the priest's feet" side by side with Isabella.