• Plan 20 to 30 minutes for the walkway loop above the ruins at kid pace, then let legs loose in Ciutadella Park, five minutes away
• Make it a spotting game: wells, drains, and street corners are all visible from above, and the site reads like a life-size map of a buried town
• Open until 8pm most of the year, with last entry to the excavation 30 minutes before closing, so it works as a late-afternoon stop

The city's grand iron market hall, built in 1876, was being turned into a library when workers found an entire block of 1700s Barcelona under the floor: streets, houses, shops and drains, left where they stood after the siege of 1714. The view over the excavation lands even with kids because it looks exactly like what it is, a buried little city. Santa Maria del Mar is three minutes away.