On both sides of the arch, just inside the doorway, is light-colored stone, a close (or exact) match to the exterior stone used to construct the building. That same color of stone is used for the flooring--U.S. stores use flooring that is considerably darker. Apple obviously wanted to provide a consistent material and color from outside to inside the store.

However, just inside these archways, the traditional stainless steel begins--you can see the standard "G5" stainless steel finish on the face of the second level.

You can see the half-circle of glass holding the Apple logo into the upper part of the arch. Barely visible at the bottom of the logo is a small conduit carrying the electrical wires for the logo lights.

In the upper left of the you can see the second level, and on the right-side the glass staircase.