That's a fantastic question! If industrial automation had its own Mount Rushmore, I'd nominate these four revolutionary technologies that truly transformed manufacturing as we know it:

1. **Programmable Logic Controllers (PLCs)** - The brain of modern automation. Before PLCs, factories relied on complex relay systems that were hard to modify. The first PLC (Modicon 084 in 1968) introduced programmable control that could be easily changed, making factories more flexible and efficient. They replaced miles of wiring with software logic!

2. **Computer Numerical Control (CNC)** - The precision master. Starting in the 1940s-50s, CNC brought computer control to machine tools, allowing for incredibly precise and repeatable manufacturing. This revolutionized everything from aerospace parts to medical devices, making complex geometries possible that were previously unimaginable.

3. **Industrial Robotics (starting with Unimate)** - The first true industrial robot installed at a GM plant in 1961. Unimate could perform dangerous, repetitive tasks with consistent quality, freeing humans from hazardous work and opening the door to 24/7 manufacturing operations.

4. **SCADA Systems** - The eyes and ears of industrial operations. Supervisory Control and Data Acquisition systems gave operators centralized monitoring and control over entire facilities, allowing real-time decision making and remote management of complex processes across vast distances.

Together, these four innovations created the foundation for modern smart factories - PLCs provide the control logic, CNC delivers precision machining, robots handle physical tasks, and SCADA gives us the big-picture oversight. What do you think - would you add or replace any of these on automation's Mount Rushmore?