Perched at the very tip of the Washington Monument is a small, pyramidal capstone made of aluminum. When it was placed on December 6, 1884, aluminum was considered a precious metal as valuable as silver because it was extremely difficult to extract and process. The capstone stands 8.9 inches tall and weighs 100 ounces. Inscribed on the east side of the aluminum tip are the Latin words "Laus Deo," which translates to "Praise be to God." In addition to its symbolic value, the capstone serves a functional purpose as part of the monument's lightning protection system; it is surrounded by several small gold-plated copper lightning rods that were added later to protect the masonry from strikes. Despite the fact that aluminum is now a common and inexpensive material, this original 19th-century capstone remains in place 555 feet above the ground, serving as a historic testament to the technological and architectural achievements of the era in which the monument was completed.