The Pantheon (Latin: Pantheon, from Greek Πάνθεον meaning "every god"), an ancient building in Rome, Italy. Built in 118–128 AD. on the site of an earlier building 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.
It is one of the best-preserved of all Ancient Roman buildings. 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 piazza is roughly rectangular, approximately 60 meters north to south and 40 meters east to west, with a fountain and obelisk in the center and the Pantheon on the south side. In the center of the piazza is a fountain, the Fontana del Pantheon, surmounted by an obelisk. The fountain was constructed by Giacomo Della Porta under Pope Gregory XIII in 1575, and the red marble Egyptian obelisk was added to it in 1711 under Pope Clement XI.
more on https://en.wikipedia.org/wiki/Pantheon,_Rome and https://en.wikipedia.org/wiki/Piazza_della_Rotonda