The interior dome and walls of the **Pantheon**, in Rome, Italy.
The structure known today as the Pantheon was originally constructed by **Marcus Agrippa** during the reign of **Augustus**. The present building was restored or completed by the emperor **Hadrian**.
Remarkably, the Pantheon has been in continuous use since the 100's CE, when it was likely dedicated by Hadrian in 126. Since the 7th century, it has been used as a Catholic church.
The dome of the Pantheon is still the largest un-reinforced concrete dome in the world, and forms a perfect half-sphere.