Standing as Ancient Rome's most perfectly preserved architectural masterpiece, the Pantheon has dominated the Eternal City's skyline for nearly two millennia, its mathematical perfection as awe-inspiring today as when it was completed around 126 CE under Emperor Hadrian. The building's defining feature—its unsupported concrete dome with the distinctive central oculus—represents the pinnacle of Roman engineering ingenuity, creating an interior space of perfect spherical harmony where the diameter exactly equals the height (142 feet). This architectural marvel doubles as a celestial instrument, with the 30-foot oculus allowing a dramatic column of sunlight to track across the interior throughout the day, connecting visitors directly with the cosmic movements above. The building's transition from pagan temple to Christian church in 609 CE ensured its preservation while adding layers of historical significance, including the tombs of Renaissance painter Raphael and Italian kings. Unlike most ancient Roman structures that survive as ruins, the Pantheon continues its original function as a public gathering space, creating an unbroken thread of human experience across centuries. The building's influence extends far beyond Rome, inspiring countless domed structures worldwide from government buildings to libraries, making it not merely a magnificent survivor from antiquity but a living architectural archetype that continues to define our understanding of monumental public space.