Need a hardcopy of the 50-title Code of Federal Regulations? This is the place. 

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster" 

Some of the most guarded conversations in Washington take place inside the hardened vaults known as SCIFs.

George L. Cassiday was a prolific Capitol Hill bootlegger who supplied hundreds of congressmen and senators with booze during Prohibition.

A crumbling network of old steam tunnels connect 24 buildings on Capitol Hill.

There's an elaborate old system of buzzers and lights in the Capitol that blast out coded messages to busy lawmakers.

Check out this National Geographic drawing of the Capitol Building.

At 8:38 am on January 15th, 1953, a man ran out of onto the Union Station concourse screaming “run for your lives!” 20 seconds later the building shook as a runaway 1,100 ton passenger train smashed through the north wall and collapsed the through the floor into the basement. 

There are several interesting conveyor systems in varying state of operation and disrepair, all designed to shuttle books around the complex.

WHY NEW CONGRESSMAN THINK WASHINGTON HEAVEN: Uncle Sam Builds Marble Palaces For Them And They Live Like Turks, Surrounded By The Comforts Of Paradise And Oriental Luxury.