Opposite the House of Vestal Virgins, the curved deception of the Temple of Romulus (the son of the emperor Maxentius), dating from 309 AD, has been sanctified and serves as vestibule for the church of Santi Cosma e Damiano behind, which sports a wide and majestic sixth-century apse mosaic showing Christ and the Apostles (entrance on Via dei Fori Imperiali). Just past the temple, a shady path to the left leads up to the Basilica of Maxentius , sometimes called the Basilica of Constantine, which rises up towards the main road - in terms of size and ingenuity probably the Forum’s most impressive remains. By the primeval fourth century, when this structure was built, Roman architects and engineers were expert at building with poured cement. Begun by Maxentius, it was continued by his co-emperor and rival, Constantine, after he had defeated him at the Battle of the Milvian Bridge in 312 AD. It’s said that Michelangelo studied the hexagonal coffered arches here when grappling with the dome of St Peter’s, and apparently Renaissance architects frequently used its apse and arches as a model. It was here that the famously fragmented colossal statue of Constantine was found, before it was moved to the courtyard of Palazzo dei Conservatori, on the Capitoline Hill.