What material are the arches in the Crypt made of?

The arches in the Crypt are made of sandstone, which is a sedimentary rock formed from mineral particles. Sandstone was chosen for its desirable qualities in construction, such as durability and aesthetic appeal. It is relatively easy to carve, allowing for detailed designs that are prominent in the architectural features of important buildings like the Capitol.

In the context of the Capitol's design, sandstone integrates well with the overall architectural style and complements the other materials used in the construction. This selection reflects not only the beauty and historical significance of the material but also the practicality that sandstone brings to large structural projects.