Conversation so far:
When did the hoover dam start being built
The Hoover Dam was constructed between 1931 and 1936 during the Great Depression
why was the hoover dam built
The Hoover Dam was built to control floods of fertile, but arid agricultural land, and to provide a source of water and electrical power for people in its adjacent areas
who was the architect of the hoover dam
Architect Gordon B. Kaufmann was brought in to design the exteriors of the Hoover Dam. Kaufmann applied an elegant Art Deco style to the entire project.

Question: who designed and decorated the walls and floors
Self-contained rewrite: who designed and decorated the walls and floors of the hoover dam