Before New York built its legendary subway system, an inventor quietly constructed a different kind of underground transit—powered not by electricity, but by air. In 1870, Alfred Ely Beach opened the Beach Pneumatic Transit beneath Broadway, a functioning subway that silently whisked passengers through a sealed tunnel using air pressure. It was revolutionary, popular—and ultimately, shut down.

This episode dives into the forgotten story of America’s earliest subway experiment, built in secret under Manhattan at a time when the city’s streets were choked with chaos. We’ll explore how political corruption, especially from Boss Tweed and Tammany Hall, crushed the project—and how the remains were unearthed decades later during construction of the modern subway system.

It’s the largest low-rise office building on Earth—and one of the most secretive. With more floor space than the Empire State Building and 17 miles of corridors, the Pentagon is the center of U.S. military command—but the public only sees a sliver of it. From forgotten tunnels to sealed war rooms, its true layout remains hidden even from most who work there.

In this episode, we uncover the forgotten history and classified secrets of the Pentagon: why it was built so fast, what lies in its deeper levels, and how its very structure was designed for control, movement, and defense. From the Pentagon Papers to lost access tunnels and internal surveillance, we reveal why this five-sided fortress is still one of the most off-limits places in America.

Before pressure valves and digital controls, American cities relied on a forgotten form of infrastructure: the standpipe. These towering vertical tubes stabilized water pressure across growing metropolises—but almost all were demolished once they became obsolete. Except in St. Louis.

Between 1871 and 1898, the city built three massive architectural towers to house its standpipes—each one more ambitious than the last. Why did St. Louis treat these utility structures like civic monuments? How did they work? And why are they still standing when every other city tore theirs down? In this episode, we explore the story of St. Louis’ hydraulic past—and the industrial monuments it left behind.