Stormwind is the human capital city, and is currently the central Alliance hub in Cataclysm, due to all of the new zones from the expansion being accessible by portals located in the city. The road to the city runs through the Valley of Heroes, which feature massive statues of the greatest Alliance historical figures.
The ruler of Stormwind is Varian Wrynn, who was not present when WoW was launched. He had been kidnapped, and in his absence, Stormwind was ruled by his young son Anduin, with Varian's good friend Bolvar Fordragon serving as custodian, and the suspicious noble Katrina Prestor as council. Through a series of quests prior to Wrath of the Lich King, the player discovers that the king's kidnapping was orchestrated by Lady Prestor, who is secretly a dragon.
When Wrath of the Lich King launched, Varian Wrynn was returned to Stormwind, and all he wanted in exchange was a humble throne to sit on.
When the player eventually discovers that a fleeing Lady Prestor is the devious dragon, Onyxia, they are given a quest to go to her lair and kill her.
When they are successful, they return with the head, which is mounted on the ramparts, and seems like a good idea at the time.
However, this does little except piss off the dragon Deathwing, who after being imprisoned underground for awhile, emerges, and causes the Cataclysm. Oh and also, he's Onyxia's father. That explains why he nukes the Stormwind Park
and parks on the Stormwind gates to cause havoc for awhile.
When he leaves, he knocks over some statues because he is a dick.