Final answer:
Gatsby's mansion is located in the fictional West Egg of Long Island, representing new wealth, as opposed to the old wealth area of East Egg.
Step-by-step explanation:
The mansion of Jay Gatsby, a central character in F. Scott Fitzgerald's novel The Great Gatsby, is located in West Egg. This fictional setting is based on the real-life area of Great Neck and Kings Point on Long Island, New York. Gatsby's lavish estate epitomizes the wealth and excess of the nouveau riche, contrasting with the more old-money area of East Egg, where characters such as Daisy and Tom Buchanan reside.