During the reign of Emperor Hadrian, one notable architectural achievement was the construction of the Pantheon in Rome, completed around 126 AD. This remarkable temple was dedicated to the Roman gods and showcased advanced engineering techniques of the time, particularly its iconic dome and oculus, which remains the world's largest unreinforced concrete dome. The Pantheon exemplified the architectural grandeur of the Roman Empire and has influenced structures throughout history. Its preservation and continued use as a church exemplify both the cultural impact of Rome and Hadrian's legacy as a builder and patron of the arts.