Musée Mécanique

In English, it is translated as "Mechanical Museum" and is a family owned collection of mostly old coin-op penny arcade games, a majority of them from the age of the between war period of WW1 and WWII. 

A picture of the entrance at it's current Fisherman's Wharf location. All pics sourced from Wikipedia. 

It's another of my fond childhood memories of going to the Cliff house in San Fran to go to the arcade, and I can't really think of anything off the top of my head to compare to it. 

The museum was started by a man named Ed Zelinsky who started his collection at age 11 and first displayed his collection at the Playland amusement park in the 1920s. After the closure of Playland in 1972, it moved to the basement of the Cliff House where it resided for most of it's operational years until moving to Fisherman's Wharf in 2002.  The move from Cliff House was said to be temporary, and was and extremely unpopular move to the locals, and it created somewhat of a controversy at the time.

Old school arm wrestling arcade game. 

The museum itself, however, is quite the enjoyable experience and feels like an interactive time capsule. Even Dan Zelinsky (the current owner and son the original founder Ed Zelinsky) who started working there in the 1970s, stated "You have to understand that people grew up with these kind of machines ... To the generation before, these were the video games. Many visitors haven't been here since childhood, but when they walk through that door, they are going back in time."

As for the exhibits themselves, Wikipedia states: The museum has a collection of over 300 mechanical games and amusement devices including music boxes, coin-operated fortune tellers, Mutoscopes, video games, love testers, player pianos, peep shows, photo booths, dioramas, and pinball machines. It displays about 200 of them at their current location. Beyond this the Museum also boasts some unique and rare historical pieces such as dioramas, a steam powered motorcycle, automatons, and even machines made of toothpicks created by prisoners of San Quentin. How's that for interesting, eh?

Even early video games can be had there. 

Many people would agree the museum is a must see for anyone visiting the San Fran area, and as an added bit of trivia, was also featured in the movie The Princess Diaries, which is the only major piece of media I can think of that includes it.