Gifted to Pope Boniface IV by Byzantine Emperor Phocas and rededicated as a Christian basilica in 
honour of St Mary and the Martyrs on this day in 609, the ancient Rome temple, built half a millennia earlier by Hadrian and commissioned to replace an earlier structure that had burnt down during the reign of Marcus Agrippa (hence the inscription, M·AGRIPPA·L·F·COS·TERTIVM·FECIT, “son of Lucius made [me] during his third term as consul,” is unique for its rotunda and oculus skylight (telling the time like a sun-dial but with light instead of shadow) and counted among the best preserved works of Roman architecture by dint of its continuous use. Though probably not a shrine sacred to the every deity since it was prescribed that temples should be devoted to a single god or goddess lest a single building be struck by lighting or be otherwise desecrated and probably a popular nickname for the many statues that lined the portico or for the vaulted ceiling that opened up to the heavens. 
In order to dispel pagan demon worship and sanctify the space, twenty-eight cartloads of remains—said to be Christians put to death during the Diocletian Persecution—were brought up from the catacombs and reinterred in a porphyry tomb beneath the altar and stripped the interior of its decoration, shipping the ornaments off to Constantinople. Used also as a final resting place for members of the House of Savoy, the interior niches have been richly decorated over the centuries and structurally is one of the most architecturally influential buildings, typifying the neo-classic style and echoed in many government buildings and public institutions.
