Andy pointed out a very cool thing about the TFA's Star Killer base - it's quite likely it was Ralph McQuarrie inspired. Who's that you may ask? He's the designer of the original look for Star Wars - the man who drew what Lucas was thinking and turned them into a visual feast.
So in terms of the Starkiller base as spied in the background of the The Force Awakens poster (See below), Andy suggested that there was an element of design taken from some concept art that McQuarrie did for the original Death Star. Note the circular 'eye' at the top of the image:
And now compare that to the image of the Starkiller base found in the TFA's official poster:
Seems familiar enough? You could argue that Death Stars and Star Killers simply need to have big round holes so the weapon can be fired through and I accept that, the point is that McQuarrie did it first.
But then..you could argue that in the McQuarrie image, that eye is not a weapon but a landing hangar...
BUT, here's some more McQuarrie concept art which shows the trench line that's similar to what is happening on the Star Killer base, and a distinct weapon hole. Help me out wise fans, what's the actual name for that?