U.S. president doffs tie to tour iconic Colosseum
Franceschini describes 'wonder, admiration' in Obama's eyes27 March, 18:10
Television footage showed a relaxed Obama asking questions of his tour guide, security agents hovering in the background.
The US president was also joined by Dario Franceschini, minister for cultural heritage who tweeted about the experience.
"I welcomed President Obama to the Colosseum. A pride for our country to see the wonder and admiration in his eyes," posted Franceschini on his Twitter feed.