• Raised walkways over the ruins let kids look straight down onto Roman streets, drains and workshops without stepping on anything
• A fish-sauce factory and a winery with sunken vats show how Barcino made garum and wine 1,800 years ago
• Ends in a medieval royal hall, the vast Saló del Tinell, so one ticket spans Roman and medieval Barcelona

Beneath Plaça del Rei lies the largest underground excavation of Roman Barcino, over 4,000 square meters of 1st-to-7th-century streets, city wall, a laundry, a dyeing workshop, a fish-salting plant and a winery, crossed on raised walkways. The route then climbs into the medieval Saló del Tinell hall and Santa Àgata chapel of the old royal palace.