Regardless of size, every city has its mysteries. In 1994, Los Angeles has more than 22,000 miles of maintained roads and freeways, a wall of civil engineering, rushing west from the deserts and spilling over into the Pacific. Mapped down to the smallest alley, it’s hard to believe it has any secrets left, but under its bustling streets, a dark labyrinth remains; thousands of miles of subterranean wash ways, carved from the landscape before the city itself, and long forgotten.