It only makes sense to anchor the sanctuary of the Greek gods to none other than New York’s most famous landmark. For those who are deemed worthy of a visit, Olympus can be found in an exclusive 600th floor, hidden to mortals. Olympian gods and goddesses meet here twice a year for winter and summer solstices. You’ll need magical proof for the guard to allow your entry. In the first book, Percy’s paraphernalia was Zeus’ stolen master bolt.