This country hold the most scariest places on planet earth and was world ruler in its historical times.Its capital is the largest metropoliton city in world.Rulers from this country were famous for their brutality and lavish life style.

England fits all the descriptions in this question. The British Empire was the largest empire in history, making it a 'world ruler.' London, England's capital, is one of the world's largest metropolitan cities. English rulers throughout history, particularly monarchs like Henry VIII, were known for both their brutality (executions, oppression) and lavish lifestyles. England also has numerous historical sites associated with dark events like the Tower of London.