Pantheon

This is from vacation in Rome and visit at Pantheon on that same trip. Pantheon was one of must visit places in Rome. It's not as big as St. Peter's Basilica, but the dome is still quite impressive.

The Pantheon is a former Roman temple, now a church. The present building was completed by the emperor Hadrian and probably dedicated about 126 AD.

The building is circular with a portico of large granite Corinthian columns 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, 43 metres (142 ft).

During 2013 Pantheon was visited by over 6 million people making it one most popular and "must visit" places in Rome.

The Pantheon's large circular domed cella, with a conventional temple portico front, is unique in Roman architecture. Nevertheless, it became a standard exemplar when classical styles were revived, and has been copied many times.

Read more in
https://en.wikipedia.org/wiki/Pantheon,_Rome