>>7916774I'll second the Spawn Alley set, it's such a great playset from a line most people kind of ignored. I didn't hear about it until long after it was done but managed to grab one for like $25 off ebay a few years back. Also, as others have said, the Click'n Play or M&C or World Peacekeepers (all of it's the same stuff) bombed out building, headquaters and quonset huts are all great pieces. I just got the latter one for xmas, though I have had neither the time, space, nor energy to bust it out yet. Another good set is the old Wayne Manor playset from the late 90s/early 00's. It was repainted a dozen times, but the basic structure of the building is really nice.
And a personal favorite of mine, a piece I've been using as Cobra Mountain since literally the 80s, is the Roboforce Fortress of Steele. It's a fold up mountain castle with a lot of high tech built in details. It's slightly bigger scale then 1:18th, but not too big where figures can't reach the controls or look silly inside of it. With a bit of work and custom accessories, it makes a great mountain fortress.
