I have participated in many free walking tours in Europe and South America. This was hands down the best. The size of the tour was restricted to a manageable size. Our guide, Stefano, kept us in rigorous formation and was both articulate and had great English. His enthusiasm was infectious. Most importantly, he had rare ability to appeal to both history geeks like myself and less intense participants. Everyone was captivated by his narrative and no one dropped off the tour because of boredom or whatever - a rare accomplishment. And although this was my fifth trip to Rome, I saw new things and learned a lot of new information. I cannot recommend this tour more highly. Just stay in advance since the size is limited and it is justifiably popular!