Storybrooke Free Public Library

The Clock Tower is in the middle of Storybrooke, and when Emma Swan arrives and stays, the clock moves. It also doubles as Storybrooke's library. It was the home to Maleficent's Dragon Form before Emma defeated her.

History
When Queen Regina cast the curse she imprisoned Maleficent in her dragon form, deep below the surface in a cave, as punishment. When Emma Swan's son Henry comes back to Storybrooke with her, they stopped outside the library and when Emma looked up to see what time it was, she noticed the clock was frozen. Henry quickly explained to her how, in his whole life, that clock had never moved, because of the curse.

Thus, everyone in Storybrooke was trapped, unable to move forward in time. While outside the library, Henry's therapist, Archie Hopper stopped to talk to the two and asked if everyone was alright. Archie revealed to Emma that the Mayor, Regina, is Henry's adoptive mother.

When Henry explained that he was with his real mom, Archie asked where he was that day because he missed his session with him, Henry told him that "he went on a field trip" and Archie advised him that lying - giving into one's dark side - never accomplishes anything (something he also advised Prince Charming about). When Archie left, Henry explained that everyone trapped within the town does not remember what had happened or their past lives in the Enchanted Forest.

Henry believed that simply bringing Emma back to Storybrooke would make time move forward, however, only when Emma decided to stay for a week in the town at Granny's Inn after she realized that Henry's adoptive mother, the Evil Queen, now known as Regina, did not truly love him.

This action causes the clock moved forward, which was an event Henry witnessed from his bedroom window. He smiles at this, knowing that Emma had decided to stay. Later, when Regina notices the clock had become unfrozen, it shocks her, and she realizes that something has gone awry.

She later brings Emma here to retrieve the True Love potion Mr.Gold had hidden in Maleficent's belly. Upon Maleficent's death, the clock tower lacks a proper purpose other than what it's supposed to be for.

Trivia

 * The clock being frozen at 8:15 is a nod to Lost, 815 was the number of the flight that crashed on the island.
 * Henry told Emma time is 'frozen' in Storybrooke and all former fairytale characters don't age. However, this has slowly started to change since Emma has come.
 * Maleficent's dragon form lived under the library, which is likely why it is boarded up.
 * The top two layers of the clock tower (including the clock) are visual effects.