Did You Know? The Washington Monument was once known to be the tallest structure in the world. Sitting at 555 feet and 5 1/8 inches tall, the memorial held this title for five years after it was completed in 1884. Then the Eiffel Tower came looming in at 984 feet. The Washington Monument has even been reported that it does in fact sway .125th of an inch when the wind blows at least 30 miles per hour.