So what was the Turtle Lair originally intended for?

[neatoman]

So why is there an abandoned apartment sized chamber with electrical output in a sewer?
No that's a serious question, what's an unused yet livable chamber doing in a sewer? What was such space intended to be used for?

I know there are some variants that make a little bit more sense (basement level apartment, mystical outpost, old pumpstation, bomb shelter, etc) but quite often it's just some unexplained chamber that just happens to be located in the sewers, bizarre huh?

[lindz247]

Well Donnie could've installed the outputs I guess...
I depends on where the big hole in the ceiling leads to. And why do they never exit through it?
I think it's where the sewage used to flow but got shut off, could have broke down and became useless to the workers so they never go there anymore.
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0CAcQjRw&url=http%3A%2F%2Fturtlepedia.wikia.com%2Fwiki%2FTu rtle_Lair&ei=L87XVOLfBYudyQTrjIHQBg&bvm=bv.85464276,d.aWw&psig=AFQjCNE807gTwYXJUJdjdzqvL02WNu-slw&ust=1423515566471249

[IndigoErth]

Maybe... A section that formerly helped negate overflow, such as during storms or a blockage in the system? Former utility space related to subway or sewer work?

The current (or former...) lair for 2012 of course has the turnstiles and stairs so I assume it's a former stop along the subway system, although the rest of the layout/design is kind of odd in that case.

[MsMarvelDuckie]

I think the OP was referring to the lair in the OT series. Myself, I always took it to be a maintenance station that workers may have used to store equipment. Also, the turtles rooms in that series looked like bricked-off tunnels, so it might have also been a junction of some sort for multiple sewer lines. I'm thinking maybe a bit of both, on further thought. So.... Junction/maintenance station? Sounds about right.

[Mew]

I was thinking similarly.