How much does the cast iron in the Capitol dome weigh?

The cast iron in the Capitol dome weighs approximately 8.9 million pounds. This specific figure reflects the substantial amount of material used in the construction of the dome, which was completed in 1866. The dome is notable not only for its architectural beauty but also for the engineering challenges it presented at the time. Understanding the weight of the cast iron is essential for appreciating both the structural integrity and the historical significance of the dome, as well as the advancements in material science during the 19th century.

Other options present different weights that do not correspond to the actual documented weight of the cast iron used. Constructing a massive dome like that of the Capitol required careful calculation of materials, making the accurate weight a significant detail in understanding its construction and durability.