Photograph of Hoover Dam, ca.1940. Oddly-shaped stone pieces protrude from the lightly-colored top of a tunnel in the foreground which intersects a castle-like, brick bridge which winds around the dark rock wall on the left. An automobile drives along the road which extends over the bridge and continues over the top of the large, lightly-colored dam at center. Cars park along the sides of the top of the dam and see electrical towers which climb from the left to the tall, jagged hills of rock in the background. To the right they see four cylindrical towers connected by walkways which stand in the smooth, shimmering water that continues out of view to the right.