The Pantheon is one of the most extraordinary monuments left from  the days of ancient Rome and is a place of unique charm. So much admiration has this temple garnered down  the centuries  that Michelangelo decided to make the cupola of Saint Peter's just a  bit smaller than that of the Pantheon, in order to leave the  Pantheon its place as Rom’s most exceptional monument: it was built  over 2000 years ago.