Hope I didn't miss a step:
From the formerly blue warped door:
Climb metal steps.
L at top, F and L at middle opening.
L, down steps until grilled door on archway.
R before this grilled door, down steps, L to arched alcove.
R and F through dark hall to end.
R, down steps and out to scaffolding.
F to columns.
F to main steps.
R down steps to main gate.
forgot to drop bread crumbs.