The Baptistery of St. John is located in Florence's Piazza del Duomo. It is one of the oldest buildings in Florence. It was built between the years 1059 and 1128. It is next to the Duomo and the Giotto bell tower.
The Baptistery is well known for its three sets of bronze doors. In 1401, Florence held a competition to build new doors for the Baptistery. A 25-year-old man named Lorenzo Ghiberti won the job and built the north doors, which were a huge hit with everyone. Later, in 1425, the Baptistery needed doors for the east side. Ghiberti was again hired and he produced a series of panels that included a "3D" look, which hadn't been seen for a thousand years. Michelangelo called these doors the "Gates of Paradise" because they were so beautiful. Many say that the Renaissance actually began in 1401, when Lorenzo Ghiberti was chosen to build the Baptistery's north doors. You can see a side-by-side comparison of the finalist's entries in the competition at Florence's Bargello Museum. The two finalists were Ghiberti and Filippo Brunelleschi. The subject was the Sacrifice of Abraham, the story of Abraham obeying God's orders to kill his only son.
The bronze doors are on the outside of the building, so they are always available for viewing. There is a small charge to go into the Baptistery. On a subsequent trip to Florence, we went inside the Baptistery to see the marvelous decorations. I was stunned at how beautiful the inside was. I hadn't expected the Baptistery to be such a wonderful, quiet refuge from the mass of tourists outside.