Can I enter with a backpack?
ZAI-no — stress on first syllable. The 'z' is voiced /dz/.
Ask before the security check at any Italian archaeological site or museum. Large bags are often required to be checked. Policy varies — important to know before queuing.
Italian museums and archaeological sites generally have bag check ('deposito bagagli') services. Large backpacks are often not allowed inside to protect artwork and archaeological remains. Small daypacks may be allowed if worn on the front. Security checks (metal detectors) are standard at major sites.
C'è un deposito bagagli?
Is there a left-luggage facility?
Ask to store large bags — usually free or small charge.
Posso tenere la borsa piccola?
Can I keep the small bag?
Clarifies whether a small bag (vs backpack) is permitted inside.
C'è un controllo di sicurezza?
Is there a security check?
Major Italian sites have airport-style security with x-ray scanners.
Security at Pompeii and the Colosseum has increased significantly since incidents of tourists removing fragments of ancient material as souvenirs. Removing even tiny pieces of ancient sites is a crime under Italian law — 'appropriazione di beni culturali' — with heavy fines.