Once Christianity became the religion of the rulers of Europe, the popes began to wield significant power and were entwined in some of the political intrigue of the period. They influenced thinking about more than religion, defining acceptable standards for art and science.
Click for larger image. But the Renaissance brought new ideas about the importance of man, and the influence of the Church slowly diminished. Ultimately, in 1929, the Vatican was established as a separate and independent country where the Catholic Church is administered without any obligation to a secular government. It is the smallest (108 acres) and most densely populated country in the world, located around the site where the Apostle Peter was buried after he was crucified by the Romans.
The bulk of the Vatican is filled by the Basilica of St. Peter. It replaced a small church on the site and was started in the early 16th century. The project was supervised, consecutively, by Branmante, Raphael and Michelangelo, and then other architects took over the work following the death of Michelangelo. You would experience the beauty of St. Peter's at it greatest if you can attend a high mass conducted by the pope. But that is an experience few foreign visitors enjoy. You will be lucky if you get a glimpse of the pope in St. Peter's square
Among the treasures of the Vatican is the gloriously painted Sistine Chapel. It is the greatest collection of Michelangelo's works as well as the place where popes are elected.
The Chronology of Popes
Drop in on the official Vatican website!
The Webfoot Guide to the Vatican