Entrance into Italy is permitted to foreigners who:
1) have a passport or valid travel document;
2) have a visa or transit document (if required);
3) have no reason that prevents them from entering a Schengen country;
4) do not present a danger to public order, national security, national health, international relations; or
5) can prove that they can maintain themselves financially while staying in Italy and have enough money to return to their country of origin (e.g. they possess a return ticket).
If any of these requisites are not fulfilled, entrance into the country can be refused.
Foreigners entering the country may be stopped and checked by the relevant border control authorities.
Foreigners who enter Italy for study, work, business, visting or tourism for a period of less than three months do not need to request a permit to stay.
People arriving from Schengen countries must submit a "dichiarazione di presenza" (see: www.poliziadistato.it/docs/telegramma_urgentissimo.pdf) within 8 days of entering Italy to the Questore of Milan (if entering Milan). If you are staying in a hotel, the hotel should provide you with the necessary form which you must sign and they will give you a copy (which you must keep as you may be requested to show it to the police if stopped). The hotel will then submit the form to the Questore (Head of Police).
People arriving from non-Schengen countries will have their passport stamped at border control and this will be considered as a "dichiarazione di presenza".
Failure to adhere to these conditions is considered an offence.