Through this passage, Fitzgerald conveys two pieces of important information:
One is the geographic context in which the story will take place. Nick's house and Gatsby's mansion on the West Egg.
And the other is the image of Gatsby that the mansion produces on the reader. The house is enormous and ostentatious, an imitation of French architecture, made of ivy and marble, with great gardens and a pool. With the description of the mansion, Fitzgerald manages to provide important information about Gatsby: he is clearly new money and he seeks to impress his neighbours and friends with it.
