What is this?

[RB101]

I've just loaded KSP up again, and this is in the VAB and SPH,

It is not a part, and persists even If I press new craft.
 

Image@ https://imgur.com/a/2131fF4

[DeadJohn]

I don't recognize that structure. It might be part of some mod that changes the VAB. What mods do you have installed?

If you want to try diagnosing it yourself, make a copy of your entire KSP folder (copy everything, not just gamedata) as a backup, then delete groups of mods at a time to narrow down which mod causes it. Restore from your backup later to undo your testing.

 

[Nazalassa]

It looks like stuff from Baikerbanur -- the old models of the pre-0.21 KSC. I don't know why theyre spawning there, but I recognize the launch tower, and the style of the other things looks similar, and I think the big thing in the middle (next to the launch tower) is the radar dish.

If you want to get to Baikerbanur, its coordinates are  20° 40′ 0″ N  146° 28′ 0″ W .