Mugu Rock is a large rock formation formed when a 200 foot deep cut was made into the rocky ridge from October 1937 to February 1940. Prior to the modern day PCH at Mugu Rock (at the time called U.S. 101 Alternate (State Route 60), drivers went around a 275 foot radius curve that is now fenced off.

The photos in the video above from the October 1940 edition of California Highways and Public Works show what it looked like before, during and after the cut was made, compared to what it looks like today.