The Richard B. Dunn Solar Telescope at Sacramento Peak in Sunspot, New Mexico, became one of the world’s leading optical solar observatories through its high-resolution imaging and spectroscopy of the Sun. Developed from a 1963 Solar Vacuum Tower Telescope design, it was built from 1966 to 1967, dedicated in 1969, and renamed in 1998 for Richard B. Dunn. Its innovative vacuum tower, much of it underground, was designed to reduce heat and turbulence that distorted solar images. The facility later supported adaptive optics and advanced instruments, influenced later large solar telescopes, and contributed important research on sunspots, magnetic fields, solar waves, and activity in the Sun’s atmosphere.