Speaking of hidden caches, the local high school where I live did a major renovation a couple of years back, and discovered a walled-up room full of equipment from back when the school hosted its own wood shop and metal shop classes, before those classes were transferred to a county vocational school location. We're talking about drill presses, lathes, welders, planers, metal brakes, and other sizable pieces of machinery, as well as hundreds of hand tools. All of that was off the books and forgotten after only a few decades, even though most of the students who had used that stuff were still alive.
Supposedly, Alexander the Great had passed the shattered ruins of what had once been a large walled city, and made inquiries with the locals about it. He was told that nobody knew the name of that city. From the path which Alexander's army took, it was presumed by later historians that the city was the remains of Nineveh, the capital of the vast Assyrian Empire at the time of its demise only a couple hundred years earlier.....totally forgotten. The site, across the river from the modern day Iraqi city of Mosul, was partially excavated over the past century and a half, but has more recently been used by rebels and terrorists as a camp, and several of the remaining stones above ground have been used as practice targets for mortar team. The next generation of archaeologists to visit the site will need to deal with unexploded mortar rounds, along with all of the other risks.
After a couple of generations, the knowledge of a nearby SL cache would fade into legend, if not plainly visible. If visible, it would inevitably be looted, at least at the surface level, before being ignored and all-but forgotten ("Yeah, I heard there's an old SL ruin there on the side of the mountain, but there's nothing left inside."). A closer examination by a more professional team might uncover a lot more.
