The Great Gatsby, solemn and mass

I'd like to know if in this excerpt from The Great Gatsby, chapter II, the word "mass" means "crowd" or "massive" and if "solemn" means "imposing", "stately" or "dreary", "lugubrious," like in "His eyes, dimmed a little by many paintless days under sun and rain, brood on over the solemn dumping ground" :

Upstairs in the solemn echoing drive she let four taxicabs drive away before she selected a new one, lavender-colored with grey upholstery, and in this we slid out from the mass of the station into the glowing sunshine.

Thank you.