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In episode 7 of "True Detective," we get frantic glimpses of Los Angeles' underground infrastructure as Officer Paul Woodrugh runs for his life. One area we see is the tunnel that links the Kenneth Hahn Hall of Administration, at the corner of Hill Street and Temple, to L.A. County Hall of Records, on the opposite corner of the street.

County workers use this tunnel on a daily basis as a faster way of getting between buildings, avoiding the congestion of downtown streets. Even when not being used for filming, the tunnel is quite sparse, with numerous pipes overhead, and a surprisingly high ambient temperature.

In October of 1960, this tunnel was the conduit for transfer of a billion dollars. At that point, many people still paid their property taxes in cash. The county which had recently moved into the Hall of Records, had to move $1 billion in push carts from the old building two blocks away to the county's new building. The county, in conjunction with the sheriff's office, spent three months planning the move, that eventually would take seven hours to fully execute.

From midnight on a Sunday until 7:30 a.m., pushcarts of money were painstakingly moved the two blocks through the tunnel under the protection of sheriff officers armed with gas grenades, shotguns and sub-machine guns. The money was moved without incident.

Staying underground, shifting four blocks southeast, sits Los Angeles' first subway, at the corner of 4th and Main. Built over the course of 18 months, the Pacific Electric Subway tunnel was assembled in hopes of elevating the already congested downtown street network. It opened on December 1st, 1925 and was christened with a bottle of ginger ale, since booze was illegal.

Sometimes called the Hollywood Subway, it did not tunnel all the way to Hollywood. Rather, it only ran for a mile before entering back into daylight, where Glendale Boulevard hits 1st Street, south of Echo Park. It did however link up with a Pacific Electric line that ran to Hollywood (hence the nickname).

At its height, the Pacific Electric system was the largest inter-urban rail system in the U.S. This mile-long tunnel was crucial in bringing passengers quickly into downtown, avoiding the already clogged streets.

The subway hit its peak in 1944, carrying 65,000 people on a daily basis, but it would be short lived.

Eleven years later, ridership had dropped off so precipitously due to the rise of the automobile, that subway was shutdown in 1955. Once shuttered, the norther portion of the subway — known as the Belmont Tunnel — would take on a second life.

LAPD parked impounded cars in this section of the tunnel. During the Cold War, 329,700 pounds of crackers were housed there; In the event of nuclear attack, it was thought Angelenos could seek refuge in the tunnel and survive on the square snack food.

During the 80s, the Belmont Tunnel rose to become the epicenter of graffiti on the West Coast. Taggers from across the world would come to leave their mark on it.

The take away from episode 7? Los Angeles' underground tunnels don't make for good escape routes.