Washington Monument - 10 Amazing Facts - as part of the travel series by GeoBeats.

10 - At about 550 feet, the monument was the tallest structure in the world when finished.

9 - The monument is the 2nd tallest stone monument and the tallest obelisk in the world.

8 - It was completed 30 years after the death of its architect, Robert Mills.

7 - Robert Mills also designed the U.S. Treasury and the Patent Office Building.

6 - The trowel used to lay foundation of the Capitol was also used in the foundation ceremony of the monument.

5 - The Washington Monument is made of nearly 36,500 blocks of marbles.

4 - There is a difference in color of the marbles which reflects monument's multiple phases of construction.

3 - There are nearly 900 steps in the monument.

2 - The inner walls consist of nearly 190 carved stones donated by various individuals, states and countries.

1 - On Dec 8th 1982, an anti-nuclear weapons fanatic was shot and killed after he threatened to blow the monument.