This happened when I was in sixth grade. My classroom had an another room attached to it (My school was a British king's place where [according to legend]his wife and daughter used to live). We weren't allowed to go inside but me and my friends always took a peek through the glass doors. It looked like a bathroom because it had an old fashioned mirror on a side, you could see pulled off pipes everywhere and even a filled pit which seemed like there was a bathtub there before. It even had two beautiful wood-carved cupboards with glass paned doors.
One day after school I was waiting for my friends to get our teacher's registers to keep them in the cupboard (I was the in-charge of the cupboards so I had the keys). We were about to leave when we heard a noise that sounded like a cupboard was flung open. When we turned we realized that the noise came from the attached room. So we decided to take a peek. We saw the silhouette a beautiful woman in a gown who seemed to be in her early twenties opening and closing the glass-paned cupboard again and again. Then she suddenly walked towards the other cupboard. We were busy looking at her when we heard a knock on the classroom door. We saw our headmistress standing near the door. Within a second we turned to the bathroom again and saw that the girl had vanished.
After that day I always went home as soon as the bell rang. My friends and I never peeked into the room again and never talked about it. But I still wanted to know more about her. So I looked on the internet and found that the girl we saw was the daughter of the British king and had died in the castle after suffering from a disease for a long time. I even asked my teacher (we were very close to each other) and she told me that my classroom including the attached room, was the princess's room itself.
Even though I was a little scared during this experience (as it was my first one) I wanted to see more and more ghosts. And I did have many more experiences after this.
I already have mentioned that only the Wife and Daughter used to live there and that was not permanent either. They went to England, sometimes even with the Viceroy. It was more like a summer cottage (but way bigger). And just in a matter-of-fact manner, there are more than three buildings in or outside Shimla. And as I already mentioned my school was many things before it became our school so it has many histories.