The grave of a martyr or saint, who died for their faith. It was not uncommon for early Christians to construct their ecclesiastical edifices over top of such a burial. This was especially prominant for the location of the apse.
An edifice built over the site of a tomb of a martyr frequently became the site of cathedrals.
A sacred place in Catholic churches where the relics of martyrs are buried, often marked by shrines for worship.