@Cosmichomicide Once upon a time, I had access to the Paramount lot. The Bell Riots episodes were filmed on a redressed New York Street, which was used time and again by many Trek series. I've been down that BART entrance; it leads to nowhere, just a concrete wall.
Follow
That's so cool! I've only been on one lot (ages ago), but yeah - the behind the scenes and the scenery were such a contrast to the final product.
@Cosmichomicide That subway entrance was originally intended to be the New York City subway, of course, but it's been redressed umpteen times. I think Harry Kim was in it in a Voyager episode.
The writers know what's on the backlot, so they write scripts to take advantage of standing sets and exteriors.
When I saw the "subway" in person, I just had to know what was down there. So I went down the steps ... and ran into a concrete wall.