The Pantheon consists out of two parts, the Portico and the Rotunda. The Portico is the entrance and is buit on to 16 massive Corinthian pillars. The Rotunda is the dome behind the Portico. In the roof of the dome there is a hole (oculus) because otherwise the structure would collapse. The maximum height of the Pantheon is 142ft. The Pantheon holds the record for the world's largest unreinforced concrete dome. The Pantheon is surrounded by normal "modern" buildings and a fountain.