The Pantheon (Pan=all + Theon=Gods) in Rome, Italy was commissioned by Marcus Agrippa in 27 BC as a temple to honor all the gods of Ancient Rome. It was later rebuilt by Emperor Hadrian in 126 AD in the domed form it retains to this day. It is among the best preserved of Rome’s ancient buildings and was highly influential to many of the great architects of all times.
Entrance to the Pantheon in Rome. Image source: http://www.silkfactory.com/2013/01/20/entrance-to-pantheon-in-rome-italy/