For instance, the Lighthouse of Alexandria (completed about 280 BC) has been estimated to be 100 m (330 ft) tall,[3] but its true height is not known. For thousands of years, the Great Pyramid in Egypt was the tallest structure in the world, but the Great Pyramid is not considered a building since it is not habitable. Similarly, the Eiffel Tower was the world's tallest structure from 1889, when it was built, until 1930, when the Chrysler Building was built.[4]