Empire State Building

The Empire State Building is a skyscraper in New York City and the current home of Olympus, the home of the gods, on the 600th floor. The Empire State Building is located at 350 5th Avenue, New York, NY 10118. The architect of this building is Shreve, Lamb and Harmon.

Description
When the center of Western Civilization in the world became America, Olympus moved itself to American in turn. It anchored itself at the top of the Empire State Building, and became hidden as the 600th floor. The Olympian gods and goddesses will meet twice a year here for the winter and summer solstices. The gods moved Olympus to the Empire State Building from it's previous position following a bright "flame" which Chiron told Percy was Western Civilization.

Magical Defenses
There is usually a security guard in the lobby who always tries to persuade demigods and mortals alike that there isn't a 600th floor. However, if you can show him something magical or make him believe you are a demigod or god, then he will give you a key enabling you to travel to Olympus. In the first book, Percy is able to travel to Olympus by showing the guard Zeus' Master Bolt. The wind gods (Aeolus, Boreas, Notus, Zephyrus) protect the top of the Empire State Building, Olympus, and the surrounding area to prevent anything from attacking from the air, forcing any possible enemies of the Olympians to use the magic elevator.

During the Battle of Manhattan, the magic that connected Olympus to the mortal world began to fade, weakening the defenses of Olympus, causing the security guard to fade. This also meant that anyone could simply walk into the elevator and take it to the 600th floor.

In the film, Sally Jackson was not able to exit the elevator to Olympus, possibly meaning that you need to be invited to Olympus or they have a magical border similar to that of Camp Half-Blood.

The Lightning Thief
When Percy first arrives at Camp Half-Blood, Annabeth mentioned a field trip the year-rounders take every year to the Empire State Building to visit Olympus on the 600th floor. Percy, being from New York wanted to tell her there was no such thing as a 600th floor, but didn't say anything. Later, after the fight with Medusa, Percy sent Medusa's Head to the gods of Olympus at the Empire State Building.

After they managed to find the Master Bolt and return to New York, Percy entered the Empire State Building and asked the security guard for a ticket to the 600th floor. While the guard originally said there was no such thing, when asked again he said that no one could see Zeus without an appointment. After Percy showed him the Master Bolt, the guard let him through to the elevator.

The Titan's Curse
After completing the Quest for Artemis, Artemis returned to Olympus to discuss plans to fight the forces of Kronos and prevent his eventual rising. Percy, along with Thalia and Annabeth took pegasi to New York and flew over the Empire State Building to reach Olympus, where the gods voted on whether Percy and Thalia would live or die.

The Last Olympian
After sinking the Princess Andromeda, Percy realized that the Titan Army was planning on attacking Olympus while the gods were busy fighting Typhon. Percy lead the camper's to New York as they used the Empire State Building as their main base, forcing the Titan's to take the elevator up if they wanted to attack Olympus (as the wind gods were protecting the skies). After a few days of fighting however, the demigod forces were pushed back all the way to the Empire State Building as their last defense and the security guard had vanished, which proved Olympus' defenses were weakened. As Kronos lead a final charge on the Empire State Building, the demigods were only saved by the timely interference of Hades and Poseidon. Kronos however managed to slip past and take the elevator up to Olympus, followed shortly by Annabeth, Percy, and Thalia.

After the battle and Kronos' defeat, Percy asked if Zeus could make the top of the Empire State Building blue (so Percy could show his mom he was alright). While confused by Percy's request, he did as he was asked. Percy later took the elevator back down to find his mother arguing with the security guard about the 600th floor of Olympus.

The Lightning Thief
The elevator in the lobby doesn't lead to Olympus; instead, Percy, Annabeth, and Sally Jackson go to the observation deck, turn off four switches in the fuse box, and then to shelves slide away and the elevator opens.

The Empire State Building is also where Luke revealed himself to be a traitor to the gods, claiming that he had planned to take over after the gods had destroyed themselves. Percy and Luke started fighting on the roof using pairs of Winged Shoes, but they eventually started fighting all over the city. Percy won and returned to the roof with the Master Bolt before taking the elevator up.

Trivia

 * The Empire State Building only appeared in the odd numbered books of the Percy Jackson and the Olympians series.
 * In the trailer for the film, Percy is seen taking the elevator to Olympus, similar to how it is done in the book. However, in the film, the way to Olympus is at the Observation Deck of the Empire State Building.