万神殿, known as the Pantheon in English, is a former Roman temple located in Rome, Italy. It was completed around 126 AD during the reign of Emperor Hadrian. The structure is famous for its large dome, which remains the world's largest unreinforced concrete dome to this day. The Pantheon is dedicated to all the gods of ancient Rome and has been remarkably well-preserved throughout the centuries. Today, the Pantheon serves as a church, officially known as Basilica di Santa Maria ad Martyres. It attracts millions of visitors each year, who come to admire its architectural beauty and historical significance. The building's oculus, a circular opening at the dome's apex, allows natural light to illuminate the interior, creating a stunning visual effect.