Running underneath the Bluff in Pittsburgh, Pennsylvania, there is a twin-bore tunnel with an unusual feature: a 45-degree bend near the northern portal. Built between 1926 and 1927, the Armstrong Tunnel was named after Joseph Armstrong, former County Director of Public Works, Commissioner, and Mayor of Pittsburgh. It was designed with a bend halfway through it to line up at a 90-degree angle with streets that run parallel, but are positioned diagonally. There are many local stories to explain the tunnel’s bend—some say that it’s the result of a mistake made…
