Where is the subway? (Fallout 4)

next to the police station there is

Alllex236 I
'll check it now, thanks

ArsenKZ
College Square kind of

Alllex236
We're talking about the grouping? According to the story quest.

oh ... sorry, you thought about metro xD

Alllex236
Okay)

I myself have not reached it yet, but I think it is located under the location of the old church. There is a puzzle in which, as I think, you need to form a word - RAILROAD I am attaching
screenshots below.