Hz → MHz
Heinrich Hertz proved electromagnetic waves exist in 1887. The unit "hertz" was adopted in 1960 in his honor.
The "War of Currents" between Edison (DC) and Tesla (AC) was partly about frequency. Tesla's 60 Hz won in the US, 50 Hz in Europe.
Pythagoras (500 BCE) discovered musical harmony ratios - a string half as long vibrates at double the frequency.
Modern CPUs run at 3-5 GHz. Quantum computers will use frequencies in terahertz range for even faster computing.
Why did the frequency go to the gym? To get more cycles per second! 🎵