Which iconic ancient Roman temple, preserved as a church, is famous for featuring the world’s largest unsupported concrete dome, illuminated solely by a central opening known as the oculus?

💡 Explanation:

The Pantheon, originally commissioned by Marcus Agrippa and rebuilt by Emperor Hadrian, boasts a magnificent dome structure. Its oculus (Latin for 'eye') is the only source of light and ventilation, remaining open to the sky.