The oldest slot machine still in use is the "Liberty Bell," which was invented by Charles Fey in 1895. It is considered the first true slot machine, featuring three reels and five symbols, including the iconic Liberty Bell. While the original machine is now a historical artifact, replicas and versions of the Liberty Bell are still used in some casinos as a nod to the early days of slot gaming. The design of the Liberty Bell laid the foundation for modern slot machines, and its legacy continues in the form of classic slots today.