I remember when Masters of the Universe first came out -- either Castle Grayskull hadn't been released with the first wave of figures or we just never saw it in stores -- but one of my older cousins built a Castle Grayskull from a cardboard box. It was
AWESOME! 
It had various chambers and even gimmicks, including a working drawbridge and trapdoor!
I didn't have any city/base-formers during the 80s, although I remember seeing someone else's Metroplex and feeling incredibly underwhelmed by its puniness. I didn't start collecting playsets until the 90s when I was a bit older; and the smaller and more affordable Micromaster bases were easier for a kid to collect.
Now if you'll excuse me, I need to get back to rocking on my porch and telling the local kids to get off my lawn.
