Its walls are 15 feet thick at the base and 18 inches at the top , and are composed primarily of white marble blocks , according to the National Park Service . The Washington Monument is declared ` ` structurally sound '' Officials decline to say when the monument will re - open to the public . Cracks were discovered after an earthquake in late August ; repairs are required . The Washington Monument is 100 feet tall .
The Washington Monument is declared ` ` structurally sound '' Officials decline to say when the monument will re - open to the public . Cracks were discovered after an earthquake in late August ; repairs are required . The Washington Monument is 100 feet tall .