Bus #13 stops at this square where the Museo di San Marco is located. #13 follows a circular route around the periphery of the old city, over a bridge and up the hill to Piazzale Michaelangelo, down the hill, over the river on a different bridge, and to the train station, then back to the Museo de San Marco. The ride is free with a Firenze Card.
There is so much to see in Florence that time is always a factor. I have to give this museum a three star rating because there is so much else to see in Florence as well. Make sure you see Santa Croce and Santa Maria Novella! And the Opera at the Duomo. If you have time come here to the Museo di San Marco. The monks' cells are interesting, each with a Fra Angelico, and other of his beautiful works are in the museum area.
The museum is free with the Firenze Card.