Crap. Does that place have a name? Shoot. I recognize it but I didn't think it had a name. Janet used a bunch of chems there, and used that place to sleep a lot.
It's the bridge right north of the Brotherhood Citadel. Alright, I just cheated a bit, had a look at the in-game map. Marigold Station, final answer!
Hmmm...your final answer is wrong but your first is correct so I'll give you the . It's right under the Arlington Bridge, as you correctly said, it's north of the Citadel. Marigold Station would be wrong.
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"I saw a politician the other day." "Horrible creatures - I avoid them whenever I can."