Which is the littlest country in the world?

Well, that's tough to answer. The Principality of Sealand exists on an abandoned oil tower, barely big enough to land a helicopter. It has been attacked by pirates once and successfully repelled the invasion. There is a similar country just outside the boundaries of Italy that was destroyed by Italian police and now exists only as a mail box in Italy where the owner sells stamps and souvenirs.

San Marino claims to be the oldest surviving sovereign state and constitutional republic in the world, 24 square miles, population about 32,000.