This signal is first discovered when the Sole Survivor activates the relay dishes at relay tower 1DL-109. The source of the signal can then be tracked to the Charles River Lock and Dam, which further leads into an interior section.
Okay, looks like a reactor malfunction in sublevel D. System locked the gates down. Again. I guess I'm gonna need a manual override. Look, Speigel: I know you've got pressing matters like reading that latest copy of La Coif to attend to. But when you find time, let me out, okay? Meanwhile I guess I'll loop this thing and have a smoke. Which is probably what you're doing up there, you lazy skeezer.
This has been a pre-recorded message. Message repeats in three seconds.
The Boston City Works beacon appears only in Fallout 4.