The Pantheon is one of Rome's most magnificent buildings. And the splendor of this domed temple, made a church (St. Mary and the Martyrs) by Pope Boniface IV, isn't lost on the kids. If you put it context, that is. Hadrian's Pantheon, 125 AD, was the first round temple ever built and it's the oldest standing domed structure in the world. The first Pantheon, built by Agrippa on the same spot 150 years earlier, looked very different from the one you see today. It was rectangular in shape like all other temples of the time. And the entrance portico faced south not north. Both Hadrian and Agrippa's temples are called the Pantheon because they were dedicated to all Roman gods. Pantheon in Greek means all gods, pan means all, teos means god. As you tour the Roman Pantheon take note of more than the tombs. (Rafael and two Italian Kings are buried here.) The height of the rotunda is the same as the diameter, 43.3 m or 142 ft. A perfect sphere! The oculus or Great Eye is the building's only source of light as well as the symbol of the sun. But more amazing still is the cupola's construction. Each tier is lighter than the previous one. Punic pumice stone, so light it floats, was used to build the highest level.