Was Pearl Harbor a ship or place?

Answer:

A place. Some port on an island in the Pacific Ocean

Answer:

Pearl harbour is a large natural harbour on Hawaii which was filled with US navy ships when the Japanese fleet launched an air attack on it.

My Answer

Pearl Harbour is two things in common usage:
  1. It was and still is a Harbour where ships stop
  2. It was the site of the opening attack by the Japanese against the USA during WWII and this event is referred to as "Pearl Harbour" EG: "I was at Pearl Harbour"

If you mean that you visited Pearl Harbour the correct way to say that is "I visited Pearl Harbour. "