Do Tourists need to carry their passorts to enter Vatican City? Where's the boundary between Rome and Vatican?

The boundary proper is not really visible, because the Swiss Guards are well within the boundaries of the Vatican State.
Look at the Vatican Web site for the "border".
Passports ? Always travel with a valid document, depending on your Nationality (EU Nationals need to carry an ID, just like Italians). If you needed a Passport for Italy, continue carrying it in the Vatican, there are no checks, but you might be challenged for Security reasons by Italian or Vatican officers. Otherwise no red tape at all.

Passports No, and the boundary is between where the guards stand outside the Vatican entrance to the left hand side. You cant wear sandals or bare feet inside St Petes.

Keith

You should always carry your passport with you when in a Foreign Country

no, if you are in italy you don't need to a passport to entry in vatica State. There is only a rupe to separete the two state..
it'a state in a city..if you are in Rome you don't need to a passaport..

io so parlare l'ialiano perch猫 i miei antenati erano italiani, per entrare al vaticano ci vuole il rosario.

no. you dont need to bring your passport with you when you enter Vatican.
anyway enjoy!Vatican is super amazing

Hi!
I live in Italy, and I have been in Rome some times.
You don't need any passport to enter Vatican.
There are no lines on the floor or any soldier on imaginary limits.
You walk there and that's all.
The only things U gotta observe:
1- U should have cover the shoulders;
2- Don't use thongs, but shoes.
Those for showing respect!

Be careful of some clever people!

Per Ravenstriker... non ti serve nemmeno il rosario.

no you dont need a passport.. you can actually just take the train from downtown rome to the vatican. it takes minutes!