Question: how long were the pyramids the tallest structure?
Evidence: The earliest structures now known to be the tallest in the world were the Egyptian pyramids: the Great Pyramid of Giza, at an original height of 146.5 m (481 ft), was the tallest structure in the world for over 3,800 years, until the construction of Lincoln Cathedral in 1311.
Answer: over 3,800
over 3,800 years