<P> The Pantheon (/ ˈpænθiən / or US: / ˈpænθiɒn /; Latin: Pantheon, from Greek Πάνθειον Pantheion meaning "(temple) of every god") is a former Roman temple, now a church, in Rome, Italy, on the site of an earlier temple commissioned by Marcus Agrippa during the reign of Augustus (27 BC--14 AD). The present building was completed by the emperor Hadrian and probably dedicated about 126 AD . He retained Agrippa's original inscription, which has confused its date of construction as the original Pantheon burnt down so it is not certain when the present one was built . </P> <P> The building is circular with a portico of large granite Corinthian columns (eight in the first rank and two groups of four behind) under a pediment . A rectangular vestibule links the porch to the rotunda, which is under a coffered concrete dome, with a central opening (oculus) to the sky . Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome . The height to the oculus and the diameter of the interior circle are the same, 142 feet (43 m). </P> <P> It is one of the best - preserved of all Ancient Roman buildings, in large part because it has been in continuous use throughout its history, and since the 7th century, the Pantheon has been used as a church dedicated to "St. Mary and the Martyrs" (Latin: Santa Maria ad Martyres) but informally known as "Santa Maria Rotonda". The square in front of the Pantheon is called Piazza della Rotonda . The Pantheon is a state property, ruled by Italy's Ministry of Cultural Heritage and Activities and Tourism through the Polo Museale del Lazio; in 2013 it was visited by over 6 million people . </P> <P> The Pantheon's large circular domed cella, with a conventional temple portico front, was unique in Roman architecture . Nevertheless, it became a standard exemplar when classical styles were revived, and has been copied many times by later architects . </P>

When was the pantheon converted into a church