This is one of the many things I have experienced through the years.
This happened in the summer of 2004. My sister, my two sons (who were 21 & 17 years old), my daughter who was only 4 years old and I were on vacation in Los Angeles and decided to go to the "Evergreen Cemetery" in Hollywood. The famous Rodolfo Valentino is in this cemetery and we decided to look for his resting place. He is in a mausoleum and we had never been in one before. We could not find Valentino’s place and were lost. About 25 minutes after we entered this mausoleum my sons came up to me and say "what is wrong with your daughter?" I got mad at them, because they were always making fun of her. I turned around to look for my daughter and saw her running from knocking on the "plaques" and saying "I’ll be there" as if some was calling her. There was nobody else in this place besides us. I observed her for a couple of minutes and then called her. My daughter was smiling and was so happy, she was acting as if she was in the happiest place in the world. While coming up to me, my daughter kept knocking on the "plaques" where people are put in (on the wall). As soon as my daughter was close to me, I asked to whom she was talking to and she answered, "the lady is dead" pointing in back of me.
There was no one there, but I was concerned and told her to tell the "lady" to go away, which she did and waved. My sons were not laughing, they looked pretty serious and by the time I was calling my daughter they were already outside waiting for us. As soon as my sister and I found Mr. Valentino’s resting place we went outside.
I talked to my sons and they were still nervous due to they could not understand why a 4 year old is knocking on the "wall" and talking to thin air. My question is, how could my daughter know that there were people in the "walls" when she had never been to a mausoleum and I didn’t take the time to tell her what this place was? Plus, she was so happy and acting as if she was in "the happiest place in the world".