When William worked in Santa Fe Springs, California, back in the 90s, he told me he thought the building he worked at was haunted. "It really is," said William. "I have had more than a few incidents happen to me while I was working alone, late at night," he continued. William was working as a manager for a very busy chemical distribution company at the time. In order to keep up with his work, he sometimes had to work at night, or go in on weekends to catch up with his paperwork.
William was a sensible man. He was not the type of person that would fly off the handle in troubling situations. He was always very calm, and composed. This is what made his story believable. I knew he wasn't the type to make things up.
One night, William went to work after dark and thought nothing of it. His former manager had told him that he might hear some weird noises coming from the warehouse, but it was only the 55-gallon drums expanding and contracting. During the heat of the day, the drums would expand, and at night, when it cooled off, the drums would contract, sometimes making a sound. William was not worried.
That night he was sitting at his desk when he heard what sounded like someone knocking on the door leading to the warehouse. William dismissed it as a drum "popping," and ignored it. A few moments later, the sound was back, and this time it was louder. Since there was no one else in the building, he became a bit nervous, but continued working. Soon the noises got louder and louder. The final straw was when he heard someone walking above the ceiling of his office. This scared him quite a bit, but again he ignored it. Finally, it happened again, and this time William ran into the warehouse to look above his office, but no one was there. After that, William never worked at night again.