When I was in Rome last month, I watched the 'synod on synodality' fizzle out while the Marko Rupnik sex scandal took another sinister turn (and various Catholic journalists shamefully tried to suppress the story). But don't worry: this episode of Holy Smoke is devoted to more uplifting matters. I visited the ancient little church of Saints Cosmas and Damian on the edge of the Forum, which incorporates the remains of a pagan temple and a secular Roman basilica or meeting place. The contrast between the darkness of one and the light of the other had powerful theological significance for those Roman Christians who were encouraged to build their first official churches by Constantine. And I was lucky to have it explained to me by one of the world's leading architectural historians, Dr Elizabeth Lev. We spoke, sometimes sotto voce, inside the little church, with tour guides and visitors swirling around us. So, apologies for the inevitable background noise, but I hope you'll agree that it doesn't get in the way of Liz's gripping narrative.