On a warm Saturday evening last autumn in Rome, I took two friends and first-time visitors, Boba and Smiljana, to Testaccio, a centrally located neighbourhood on the left bank of the Tiber River. We went to a party held twice a month at the Mercato di Testaccio (Testaccio Market), when stalls stay open late, offering classic Roman dishes like cacio e pepe, carbonara and supplì (deep-fried risotto balls) – alongside wine, beer and music.