Anybody know what this is?

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Anybody know what this is?

It's a gated stairway on the corner of Santa Monica and Normandie in L.A. (technically, Hollywood).

Is this an entrance to the old subway they built 90 years ago? (Additional info: There's an identical one on the other side of Santa Monica Blvd.)

UPDATE: Here’s the answer, provided by the L.A. Times via Julian Gomez in a comment below.