Standing almost due east of the Reflecting Pool and the Lincoln Memorial, the monument, made of marble, granite, and bluestone gneiss, is both the world's tallest stone structure and the world's tallest obelisk, standing 555 feet 7 11⁄32 inches (169.351 m) tall.t the time of its completion, it was the tallest building in the world, a title it retained until the Eiffel Tower was completed in 1889; however, the Washington Monument is still the tallest stone structure in the world.