I visited Vatican City my second day in Roma. The smallest country in the world has a population of less than 1000 on only 110 acres. You can pan out in the Google Map below to see how tiny the Vatican State actually is. It lies wholly within Roma, with no immigration check. You do not need a passport to enter the Vatican City. By land size, Roma is 2888 bigger than Vatican City. By population, Roma is 3403 times bigger than Vatican City.
Ostensibly, Vatican City serves the most important Catholic functions in the world. To everyone who visits it, Vatican City is merely an awesome tourist destination.
From my hotel in the middle of Roma, I walked about 45 minutes and 3.5 kilometers to reach Vatican City. Roma is full of stunning architecture so there is little need to take a taxicab.
Even amid the glory of Roma, you could assume you are in a different country when you step into the majestic Piazza San Pietro. There is literally only a white line to demarcate the border between this Piazza and the country of Italia.
Since I have been traveling in the months of November and December, the crowds have been much lighter than they would be during the summer. In Paris and Barcelona, it was not as obvious to me, but Venezia was a ghost town. Roma has plenty of energy without tourists, but I regularly ignored online reservations because I knew the queues would be nonexistent. Frequently at attractions, I saw many barricades that were to keep multi-hour summer lines in check but to me were smug reminders of the benefits of traveling during winter. The weather has been great throughout, and the thought of waiting in line for a couple of hours in searing heat sounds dreadful. If you go to Roma during the summer, you must make online reservations at a few of these attractions to minimize queue time, although annoyingly, there is a €2 surcharge for online bookings.
After visiting the Basilica di San Pietro, I went to Musei Vaticani (€16), which are an impressive collection of art and artifacts from around the world. Before I arrived, I thought the art would be mostly religious and local in nature, but the impressive plunder comes from a variety of besieged civilizations. I spent nearly three hours at the museums, but I could have easily spent twice that amount.
Vatican City is not a member of the 18-state European Union, but it stills uses the Euro. Euro coins have a map of Europe as the reserve side, but each country has its own obverse design, including Vatican City. In the highly unlikely event that you come upon a Euro coin from the Vatican City, do not use it because its rarity makes it worth more than its face value.