The oldest keys known to exist date from around 4,000 BC in Ancient Egypt. These were simple wooden cylinders that were part of a mechanism to secure doors. By the time of the Roman Empire, metal keys were in common usage and had begun to adopt the recognizable pattern of keys today. This book tells the complete story of the key, backed by numerous photos from all time periods. Today, old keys are more than just security mechanisms. They are highly collectable artifacts that can either be artistically beautiful or coldly functional, but either way, they can help us unlock the secrets of the past.