It used to be, and probably still is, a rite of passage for young hackers to learn how to pick locks. I believe this started at MIT where the idea of locked /anything/—software, doors, …—was an anathema, and challenge, to the hackers there who could not let such things stand. This resulted in the infamous MIT Guide to Lock Picking.
You may think that it requires a lot of skill and practice but actually picking a modern pin tumbler lock is pretty easy. Is there such a thing as an unpickable lock? Almost certainly not but in the 1800s in Britain, two inventors, Joseph Bramah and Jeremiah Chubb each claimed to have invented an unpickable lock. These weren’t idle boasts. Bramah offered a substantial prize for anyone who could pick his lock and that prize went unclaimed for 67 years. Chubb’s lock was adopted by the British Government after substantial vetting. Both locks were defeated in 1851 by an American locksmith and inventor, Alfred C. Hobbs.
The story of these two locks is amusingly told by Arran Loomas in the video Could You Pick The Unpickable Lock? He tells the story of the locks, how they operated, and how Hobbs was finally able to pick them. For a brief span of almost 70 years, unpickable locks did exist. The video is 14 minutes, 27 seconds long.
If you like this sort of thing and are wondering what a modern day “unpickable” lock might look like, consider the Browley lock. The LockPickingLawyer has an excellent video that shows how it works and why it’s so hard to pick. That video is 17 and a quarter minutes long.