What were the innovations of the roman pantheons?

The Roman Pantheon, completed around 126 AD under Emperor Hadrian, is renowned for its architectural innovations, particularly its massive concrete dome, which remains the largest unreinforced concrete dome in the world. The oculus at the dome's apex allows natural light to illuminate the interior while also reducing the weight of the structure. Additionally, the use of coffered ceilings not only adds aesthetic appeal but also further lightens the dome. These innovations exemplify the Romans' advanced engineering skills and their ability to create monumental spaces that influenced architecture for centuries.