In May 1980, I was serving with the military in Germany. This occurred at Coburg Castle. While I used most of my free time to explore old battlefields and castles, this incident to this day weirds me out when thinking about it.
It was a nice clear day, and while taking a tour of the local castle I found myself on a wall staring down an open field bordered by trees down into the city itself. I felt a strange tingle in my folded arms and grabbed the wall as it spread through me.
It felt like I was about to throw up or pass out. I looked down for a place to sit, but when I looked up, the city was gone. In fact, only a small, ancient-looking cluster of building could be seen in the far distance. I looked down and shook my head in disbelief. When I looked up, everything was normal again.
My friend said he thought I was having a seizure, so we got down off the wall. As I sat there trying to get my mind working right, I saw a metallic object partially sticking out of the hard-packed dirt in front of me. I pulled it out and it was a small necklace with German writing (the emblem was from a local town).
I put it in my pocket, and as I got up I looked up and noticed we had been sitting directly under the wall where my strange incident happened. For some reason I felt I was meant to find that necklace. To this day, I still have it.