The Colosseum is an elliptical building measuring 189 meters long and 156 meters wide with a base area of 24,000 m² with a height of more than 48 meter. The marble façade and some parts of the Colosseum were used for the construction of St Peter’s Basilica and later monuments.
The Pantheon 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). It was completed by the emperor Hadrian and probably dedicated about 126 AD. Its date of construction is uncertain, because Hadrian chose not to inscribe the new temple but rather to retain the inscription of Agrippa's older temple, which had burned down. Interesting story!