It's official number of inhabitants is lower than 1,000 and it is completely encircled by Rome, the Eternal City and capital of Italy. Hence, it is a state within a capital, which obviously also is a unique feat in the world. It's sole reason for existence is, of course, the Seat of the Roman Catholic Church, and its head of state no other than the Pope. The St. Peter is always present, and you are unfailingly attracted to it. Once inside, you are overwhelmed and dwarfed by the enormous Basilica.
Sounds seem to come fro everywhere.
Even for those of us who are not religious, a visit is always impressive, and the place certainly has a special feel. The Vatican cannot be left without a visit to the treasures of the Sistine Chapel and the Vatican Museum which is completely full with highly interesting pieces.