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" 

The streetcars themselves are long gone, you can find some scattered infrastructure around town if you know where to look.

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

The redevelopment project will transform the neighborhood east of Howard University with the addition of 600 housing units, a park, new commercial space, and expanded offices for the nearby Children's Hospital. 

The gap in the center can be filled in with post and panels that can hold back waters up to 19 feet above sea level.

Before the National Portrait Gallery requisitioned the space in 1962, this beautiful room was the Patent Office's model hall. 

"The catacombs are constructed in three levels, with steps and iron pipe ladders leading between different tiers."

You may have walked by this stately Beaux Arts mansion on New Hampshire Avenue. That's the Perry Belmont House, built in 1909 for the eponymous millionaire congressman from New York. 

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

The Spring Valley neighborhood next to American University is built on top of a World War I-era chemical weapons experiment station. 

“Raw water” came in from the reservoir and slowly percolated through the sand filters in 25 vaulted underground cells before making its way out into District taps.

The tunnel project was a “monument of fraud” that dragged on for decades and came in millions of dollars over budget.

Cold War tensions escalated on August 12th, 1961 as Communist soldiers sealed off West Berlin with barbed wire barricades. In Washington, construction of a different sort was also underway that day, as the White House Signal Agency moved forward with a top secret communications facility in Tenleytown.