The open Central Courtyard, with its gigantic "Grand Portal" Arch. This was modeled after a set built for D.W. Griffith's silent-era epic "Intolerance" (1916).
Photo from

A still from "Intolerance", showing the original Arch. After shooting was completed, the set was moved to the intersection of Sunset and Vine. It stood there for several years before being demolished.
Photo from Wikipedia / "Ihcoyc"