De Ceremoniis
The church's mausoleums were the resting place for most Eastern Roman emperors and members of their families for seven centuries, beginning with Constantine I (d. 337) and ending with Constantine VIII (d. 1028). With no more space available at that time, emperors began to be buried in other churches and monasteries around the city. The tombs located at the church of Holy Apostles are known only from lists in literary sources, one of which is contained in De Ceremoniis.