Florence's Accademia Gallery (Galleria dell'Accademia) sits second on most itineraries, right after the fabulous Uffizi. The collection at the Accademia can't compare to the Uffizi in terms of size or variety, but it has one must-see sight that the Uffizi can't claim—Michelangelo's staggering Statue of David.
The Accademia building housing the piece was built in the late 19th century specifically so that the statue could be moved there. You'll notice how perfectly the spot suits such a masterpiece, which is quite literally by design. Although the David is unquestionably the focus of a visit to the Accademia, it's far from the only thing worth checking out inside the gallery.
The short hall before you reach the David is lined with other Michelangelo statues—an unfinished series called “Prisoners,” similar to the unfinished “Slaves” in the Louvre, and an unfinished statue of Saint Matthew.
There are also some 15th- and 16th-century paintings on display by artists such as Botticelli, Ghirlandaio and Uccello, as well as a plaster of Giambologna's “Rape of the Sabine Women.” Oddly, among all this Florentine artwork, there is also a small collection of Russian icons in the gallery.
The Accademia Gallery is a 10-minute walk east of the train station. It's next door to Piazza San Marco, so visitors often take the opportunity to also see the sublime frescoes by Fra Angelico in the convent of San Marco.