We all know Michelangelo's David.
Traditionally, David was portrayed after his victory, triumphant over Goliath. Both Verrochio's and Donatello's Davids are depicted standing over Goliath's severed head. Michelangelo has depicted David before the battle. Davis is tense, but not so much in a physical as in a mental sense. The slingshot he carries over his shoulder is almost invisible, emphasizing that David's victory was one of cleverness, not sheer force. This interpretation comes from Gardner's art through the ages. Irving Stone is somewhat more specific in stating that David is depicted at the moment that he decides to engage Goliath.
Michelangelo was a citizen of the city state of Firenze (Florence). The national state of Italy is very young, and in the time the statue was made (between 1501 and 1504), power resided with individual cities. Firenze was surrounded by enemies that much stronger and more numerous than the city was. When the statue of David was placed on the square in front of the city hall (where you can now find a copy), the people of Firenze immediately identified with him, as a cunning victor over superior enemies. To them, David was a symbol representing fortezza and ira, strength and anger. The statue had (intended) political connotations for the city state that had recently cast of the ruling of the Medici family. Note how David's character traits, are considered more important than his victory over Goliath, which is why Michelangelo depicted him before the battle, strong-willed and ready to fight.
Nowadays, you can find David in the Galeria dell'Academia in Firenze. You'll find him among other statues by Michelangelo, some of which are only half finished, which in my opinion makes them even more impressive. There are two more copies of David in Firenze, one in front of the old city hall, and one on a hill overlooking the city.
Here are some references in case you are interested in Michelangelo, in David, or just in art in general. These books do a much better job of presentation that any web site does.
The statue of David was started by a different artist, Agostino di Duccio, in 1463. He picked out a rather narrow piece of stone, which was customary for artists of his denomination. If you are an art expert, you can see from the side that this is not a piece that Michelangelo would have picked. It is too thin. The front however, did not come out too bad...
Here are some interesting links: