What U.S. landmark was built on a mudflat known as "Hell's Bottom"?

In the U.S., the well known landmark that was built on a mudflat known as "Hell's Bottom" is The Pentagon. This building was officially opened on January 15, 1943. At the time, it was by far the largest office space in the world. It has 17.5 miles of corridors and a total floor area of 6.6 million square feet. It is a military complex that was designed to be like no other in the world.

Today, The Pentagon owes its unique shape to the fact that it was built at a different planned location. Several sites had been considered for the new military complex. The original choice was a sprawling stretch of land just east of Arlington Cemetery. It was land that once belonged to Confederate General Robert E. Lee. At that time, the tract was managed by the Department of Agriculture (DOA).

Because of major concerns about where the complex should be located, President Roosevelt picked the site that had once been home to Hoover Field. This was the place which included "Hell's Bottom" and became the first airport to serve the Washington, D.C., area. When it became too late to start a new design process, the pentagon shape remained. Its five sides were straightened and smoothed to the more standard form everyone sees today.