Florence is such a famous place, so many of you have come to see it, and so much information is available on the famous sites in Florence in books and on the Internet, that I decided to share photos by focusing on specific groups of amazing things rather than on each of the famous buildings.
As a starter, I find the floors in most of the famous buildings amazing. Here are just a few, with their locations.
First the floor in the Duomo (the Cattedrale di Santa Maria del Fiore), laid with marble tiles…

I understand that the center of the floor under the dome in the Duomo (not in the photo) was used by a cosmographer Paolo Toscanelli to help map patterns of the movement of the sun; he is best known for sending a map to Christopher Columbus which was then used to sail to the new world.
[Update: I found a picture of the floor under the dome–the center marker under the dome is at the top of the photo.]

[Update: Under the Duomo you can find the archaeological remains of both a medieval church and some Roman ruins, including this floor with the mosaic partly intact.]
Nearby the cathedral is the magnificent Baptistery (one of my favorite places in Florence). The floors match other parts of the building (ceiling photos soon to come) in detail and complexity.
This floor in the San Lorenzo Library, which was designed by Michelangelo, is still the original floor. The skulls in the floor don’t really show in the photo, but why did Michelangelo include them, I wonder.
The floors in the Medici Chapels were well matched with the walls (you get an early look at a wall). So many colors of marble were used.
The Basilica of Santa Croce had similar beautiful stone work in the floors, but the floors also had gravestones or memorial stones they let us walk on (unless the person was especially famous–you can see the ropes around one grave).
The stone on the left below is for Lorenzo Ghiberti, the man who made the bronze doors on the Baptistery at the Duomo.
To remind you how beautiful the Ghiberti doors are, here are a couple of pictures from the replacement doors (the real ones are in the Duomo Museum and I didn’t take a photo).
Who did all this beautiful work on the floors for people to walk on?
[Update: 5/8/2016….after a visit to the Cathedral in Siena]
The floors in the Cathedral in Siena are spectacular. The general marble patterns were beautiful in and of themselves, but….
over a multi-decade period using more than 40 artist, depictions of Old and New Testament stories were created. The first example is of King David on this throne.

One very moving piece was large and hard to photograph–I tried a panoramic shot, but you can see the arm of another man taking a photo on the right….and I had to stop before I got to the end of the piece. It is the Slaughter of the Innocents.

The details show Herod on this throne and the soldiers attacking mothers and children.
Only for a few weeks each year are all the floors uncovered. Many were covered by carpets and protected by rope barriers.
Even the marble that was only itself–not decorated or inlaid with multiple colors or patterns is quite amazing and if all that is not enough, the hallway to the bookstore and restrooms was also nice (on the right).
I advise a visit for yourself.